diff --git a/client/src/components/preview-modal.tsx b/client/src/components/preview-modal.tsx
new file mode 100644
index 0000000..5e1f55a
--- /dev/null
+++ b/client/src/components/preview-modal.tsx
@@ -0,0 +1,335 @@
+import { useState, useEffect } from 'react';
+import { Dialog, DialogContent, DialogHeader, DialogTitle, DialogDescription } from '@/components/ui/dialog';
+import { Button } from '@/components/ui/button';
+import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from '@/components/ui/select';
+import { ChevronLeft, ChevronRight, Send, Facebook, Instagram, Heart, MessageCircle, Share2, Bookmark } from 'lucide-react';
+import type { Media } from '@shared/schema';
+
+interface PreviewModalProps {
+  open: boolean;
+  onOpenChange: (open: boolean) => void;
+  postText: string;
+  selectedMedia: string[];
+  mediaList: Media[];
+  onPublish: () => void;
+  isPublishing: boolean;
+}
+
+type PreviewFormat = 'facebook-feed' | 'instagram-feed' | 'instagram-story';
+
+export function PreviewModal({
+  open,
+  onOpenChange,
+  postText,
+  selectedMedia,
+  mediaList,
+  onPublish,
+  isPublishing
+}: PreviewModalProps) {
+  const [previewFormat, setPreviewFormat] = useState<PreviewFormat>('facebook-feed');
+  const [currentPhotoIndex, setCurrentPhotoIndex] = useState(0);
+
+  const orderedMedia = selectedMedia
+    .map(id => mediaList.find(m => m.id === id))
+    .filter((m): m is Media => m !== undefined);
+
+  // Reset photo index when modal opens or media changes
+  useEffect(() => {
+    if (open) {
+      setCurrentPhotoIndex(0);
+    }
+  }, [open, selectedMedia.length]);
+
+  const nextPhoto = () => {
+    setCurrentPhotoIndex((prev) => (prev + 1) % orderedMedia.length);
+  };
+
+  const prevPhoto = () => {
+    setCurrentPhotoIndex((prev) => (prev - 1 + orderedMedia.length) % orderedMedia.length);
+  };
+
+  const goToPhoto = (index: number) => {
+    setCurrentPhotoIndex(index);
+  };
+
+  const getMediaUrl = (media: Media) => {
+    if (previewFormat === 'facebook-feed') {
+      return media.facebookFeedUrl || media.originalUrl;
+    } else if (previewFormat === 'instagram-feed') {
+      return media.instagramFeedUrl || media.originalUrl;
+    } else {
+      return media.instagramStoryUrl || media.originalUrl;
+    }
+  };
+
+  const renderFacebookFeed = () => (
+    <div className="bg-white rounded-lg overflow-hidden border border-gray-200 max-w-lg mx-auto">
+      {/* Header */}
+      <div className="p-3 flex items-center gap-3 border-b border-gray-200">
+        <div className="w-10 h-10 rounded-full bg-blue-500 flex items-center justify-center">
+          <Facebook className="w-6 h-6 text-white" />
+        </div>
+        <div className="flex-1">
+          <div className="font-semibold text-sm text-gray-900">Votre Page</div>
+          <div className="text-xs text-gray-500">À l'instant</div>
+        </div>
+      </div>
+
+      {/* Text */}
+      {postText && (
+        <div className="p-3 text-sm text-gray-900 whitespace-pre-wrap">
+          {postText}
+        </div>
+      )}
+
+      {/* Media Carousel */}
+      {orderedMedia.length > 0 && (
+        <div className="relative bg-black">
+          <img
+            src={getMediaUrl(orderedMedia[currentPhotoIndex])}
+            alt={`Photo ${currentPhotoIndex + 1}`}
+            className="w-full h-auto"
+          />
+          {orderedMedia.length > 1 && (
+            <>
+              <button
+                onClick={prevPhoto}
+                className="absolute left-2 top-1/2 -translate-y-1/2 w-8 h-8 bg-white/90 rounded-full flex items-center justify-center hover:bg-white transition-colors"
+                data-testid="button-prev-photo"
+              >
+                <ChevronLeft className="w-5 h-5" />
+              </button>
+              <button
+                onClick={nextPhoto}
+                className="absolute right-2 top-1/2 -translate-y-1/2 w-8 h-8 bg-white/90 rounded-full flex items-center justify-center hover:bg-white transition-colors"
+                data-testid="button-next-photo"
+              >
+                <ChevronRight className="w-5 h-5" />
+              </button>
+              <div className="absolute bottom-3 left-1/2 -translate-x-1/2 flex gap-1.5">
+                {orderedMedia.map((_, idx) => (
+                  <button
+                    key={idx}
+                    onClick={() => goToPhoto(idx)}
+                    className={`w-2 h-2 rounded-full transition-colors ${
+                      idx === currentPhotoIndex ? 'bg-white' : 'bg-white/50'
+                    }`}
+                    data-testid={`button-photo-indicator-${idx}`}
+                  />
+                ))}
+              </div>
+            </>
+          )}
+        </div>
+      )}
+
+      {/* Actions */}
+      <div className="p-3 flex items-center gap-4 border-t border-gray-200">
+        <Heart className="w-5 h-5 text-gray-600" />
+        <MessageCircle className="w-5 h-5 text-gray-600" />
+        <Share2 className="w-5 h-5 text-gray-600" />
+      </div>
+    </div>
+  );
+
+  const renderInstagramFeed = () => (
+    <div className="bg-white rounded-lg overflow-hidden border border-gray-200 max-w-lg mx-auto">
+      {/* Header */}
+      <div className="p-3 flex items-center gap-3">
+        <div className="w-8 h-8 rounded-full bg-gradient-to-tr from-yellow-400 via-pink-500 to-purple-600 flex items-center justify-center">
+          <Instagram className="w-5 h-5 text-white" />
+        </div>
+        <div className="flex-1">
+          <div className="font-semibold text-sm text-gray-900">votre_page</div>
+        </div>
+      </div>
+
+      {/* Media Carousel */}
+      {orderedMedia.length > 0 && (
+        <div className="relative bg-black aspect-square">
+          <img
+            src={getMediaUrl(orderedMedia[currentPhotoIndex])}
+            alt={`Photo ${currentPhotoIndex + 1}`}
+            className="w-full h-full object-cover"
+          />
+          {orderedMedia.length > 1 && (
+            <>
+              <button
+                onClick={prevPhoto}
+                className="absolute left-2 top-1/2 -translate-y-1/2 w-8 h-8 bg-black/50 rounded-full flex items-center justify-center hover:bg-black/70 transition-colors"
+                data-testid="button-prev-photo"
+              >
+                <ChevronLeft className="w-5 h-5 text-white" />
+              </button>
+              <button
+                onClick={nextPhoto}
+                className="absolute right-2 top-1/2 -translate-y-1/2 w-8 h-8 bg-black/50 rounded-full flex items-center justify-center hover:bg-black/70 transition-colors"
+                data-testid="button-next-photo"
+              >
+                <ChevronRight className="w-5 h-5 text-white" />
+              </button>
+              <div className="absolute top-3 left-1/2 -translate-x-1/2 flex gap-1">
+                {orderedMedia.map((_, idx) => (
+                  <button
+                    key={idx}
+                    onClick={() => goToPhoto(idx)}
+                    className={`h-1 flex-1 transition-colors rounded ${
+                      idx === currentPhotoIndex ? 'bg-white' : 'bg-white/50'
+                    }`}
+                    style={{ width: '40px' }}
+                    data-testid={`button-photo-indicator-${idx}`}
+                  />
+                ))}
+              </div>
+            </>
+          )}
+        </div>
+      )}
+
+      {/* Actions */}
+      <div className="p-3 flex items-center gap-4">
+        <Heart className="w-6 h-6" />
+        <MessageCircle className="w-6 h-6" />
+        <Share2 className="w-6 h-6" />
+        <Bookmark className="w-6 h-6 ml-auto" />
+      </div>
+
+      {/* Text */}
+      {postText && (
+        <div className="px-3 pb-3">
+          <span className="font-semibold text-sm">votre_page</span>
+          <span className="text-sm ml-2">{postText}</span>
+        </div>
+      )}
+    </div>
+  );
+
+  const renderInstagramStory = () => (
+    <div className="bg-black rounded-lg overflow-hidden max-w-sm mx-auto" style={{ aspectRatio: '9/16' }}>
+      {/* Header */}
+      <div className="absolute top-0 left-0 right-0 p-3 flex items-center gap-3 z-10">
+        <div className="w-8 h-8 rounded-full bg-gradient-to-tr from-yellow-400 via-pink-500 to-purple-600 flex items-center justify-center">
+          <Instagram className="w-5 h-5 text-white" />
+        </div>
+        <div className="flex-1">
+          <div className="font-semibold text-sm text-white drop-shadow-lg">votre_page</div>
+        </div>
+      </div>
+
+      {/* Media */}
+      {orderedMedia.length > 0 && (
+        <div className="relative h-full">
+          <img
+            src={getMediaUrl(orderedMedia[currentPhotoIndex])}
+            alt={`Story ${currentPhotoIndex + 1}`}
+            className="w-full h-full object-cover"
+          />
+          {orderedMedia.length > 1 && (
+            <>
+              <div className="absolute top-3 left-3 right-3 flex gap-1">
+                {orderedMedia.map((_, idx) => (
+                  <button
+                    key={idx}
+                    onClick={() => goToPhoto(idx)}
+                    className={`h-1 flex-1 transition-colors rounded-full ${
+                      idx === currentPhotoIndex ? 'bg-white' : 'bg-white/50'
+                    }`}
+                    data-testid={`button-photo-indicator-${idx}`}
+                  />
+                ))}
+              </div>
+              <button
+                onClick={prevPhoto}
+                className="absolute left-2 top-1/2 -translate-y-1/2 w-10 h-10 bg-black/30 rounded-full flex items-center justify-center hover:bg-black/50 transition-colors"
+                data-testid="button-prev-photo"
+              >
+                <ChevronLeft className="w-6 h-6 text-white" />
+              </button>
+              <button
+                onClick={nextPhoto}
+                className="absolute right-2 top-1/2 -translate-y-1/2 w-10 h-10 bg-black/30 rounded-full flex items-center justify-center hover:bg-black/50 transition-colors"
+                data-testid="button-next-photo"
+              >
+                <ChevronRight className="w-6 h-6 text-white" />
+              </button>
+            </>
+          )}
+          {/* Text overlay */}
+          {postText && (
+            <div className="absolute bottom-20 left-0 right-0 p-4">
+              <div className="bg-black/50 backdrop-blur-sm rounded-lg p-3">
+                <p className="text-white text-sm text-center">{postText}</p>
+              </div>
+            </div>
+          )}
+        </div>
+      )}
+    </div>
+  );
+
+  return (
+    <Dialog open={open} onOpenChange={onOpenChange}>
+      <DialogContent className="max-w-4xl max-h-[90vh] overflow-y-auto">
+        <DialogHeader>
+          <DialogTitle>Prévisualisation de la publication</DialogTitle>
+          <DialogDescription>
+            Visualisez votre publication avant de la publier
+          </DialogDescription>
+        </DialogHeader>
+
+        <div className="space-y-6">
+          {/* Format selector */}
+          <div className="flex items-center gap-4">
+            <label className="text-sm font-medium">Format de prévisualisation:</label>
+            <Select value={previewFormat} onValueChange={(value: PreviewFormat) => {
+              setPreviewFormat(value);
+              setCurrentPhotoIndex(0);
+            }}>
+              <SelectTrigger className="w-64" data-testid="select-preview-format">
+                <SelectValue />
+              </SelectTrigger>
+              <SelectContent>
+                <SelectItem value="facebook-feed" data-testid="option-facebook-feed">
+                  Feed Facebook (1200x630)
+                </SelectItem>
+                <SelectItem value="instagram-feed" data-testid="option-instagram-feed">
+                  Feed Instagram (1080x1080)
+                </SelectItem>
+                <SelectItem value="instagram-story" data-testid="option-instagram-story">
+                  Story Instagram (1080x1920)
+                </SelectItem>
+              </SelectContent>
+            </Select>
+          </div>
+
+          {/* Preview */}
+          <div className="border rounded-lg p-6 bg-gray-50">
+            {previewFormat === 'facebook-feed' && renderFacebookFeed()}
+            {previewFormat === 'instagram-feed' && renderInstagramFeed()}
+            {previewFormat === 'instagram-story' && renderInstagramStory()}
+          </div>
+
+          {/* Actions */}
+          <div className="flex justify-end gap-3">
+            <Button
+              variant="outline"
+              onClick={() => onOpenChange(false)}
+              data-testid="button-cancel-preview"
+            >
+              Annuler
+            </Button>
+            <Button
+              onClick={onPublish}
+              disabled={isPublishing}
+              className="bg-gradient-to-r from-primary to-secondary hover:opacity-90"
+              data-testid="button-publish-from-preview"
+            >
+              <Send className="w-4 h-4 mr-2" />
+              {isPublishing ? 'Publication...' : 'Publier'}
+            </Button>
+          </div>
+        </div>
+      </DialogContent>
+    </Dialog>
+  );
+}
diff --git a/client/src/pages/new-post.tsx b/client/src/pages/new-post.tsx
index b165cdf..35f2d7e 100644
--- a/client/src/pages/new-post.tsx
+++ b/client/src/pages/new-post.tsx
@@ -32,6 +32,7 @@ import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from "@
 import { useToast } from "@/hooks/use-toast";
 import { apiRequest, queryClient } from "@/lib/queryClient";
 import type { SocialPage, Media } from "@shared/schema";
+import { PreviewModal } from "@/components/preview-modal";
 
 function SortableMediaItem({ 
   media, 
@@ -109,6 +110,7 @@ export default function NewPost() {
   const [generatedVariants, setGeneratedVariants] = useState<any[]>([]);
   const [postText, setPostText] = useState('');
   const [postType, setPostType] = useState<'feed' | 'story' | 'both'>('feed');
+  const [previewModalOpen, setPreviewModalOpen] = useState(false);
 
   const { data: pages = [] } = useQuery<SocialPage[]>({
     queryKey: ['/api/pages'],
@@ -675,19 +677,29 @@ export default function NewPost() {
               </Card>
 
               <Button 
-                onClick={handleCreatePost}
+                onClick={() => setPreviewModalOpen(true)}
                 disabled={createPostMutation.isPending}
                 className="w-full bg-gradient-to-r from-primary to-secondary hover:opacity-90 shadow-lg"
                 size="lg"
-                data-testid="button-create-post"
+                data-testid="button-preview-post"
               >
                 <Send className="w-4 h-4 mr-2" />
-                {createPostMutation.isPending ? 'Création...' : 'Créer la publication'}
+                Prévisualiser et publier
               </Button>
             </div>
           </div>
         </div>
       </main>
+      
+      <PreviewModal
+        open={previewModalOpen}
+        onOpenChange={setPreviewModalOpen}
+        postText={postText}
+        selectedMedia={selectedMedia}
+        mediaList={mediaList}
+        onPublish={handleCreatePost}
+        isPublishing={createPostMutation.isPending}
+      />
     </div>
   );
 }