diff --git a/src/core/feedsmodel.cpp b/src/core/feedsmodel.cpp
index f67e7573f..f75ddf96a 100755
--- a/src/core/feedsmodel.cpp
+++ b/src/core/feedsmodel.cpp
@@ -28,6 +28,7 @@
 #include <QSqlQuery>
 #include <QSqlRecord>
 #include <QPair>
+#include <QStack>
 
 #include <algorithm>
 
@@ -522,10 +523,51 @@ QModelIndex FeedsModel::indexForItem(FeedsModelRootItem *item) const {
 
 bool FeedsModel::mergeRootItem(FeedsModelRootItem *root_item, QString &output_message) {
   if (root_item == NULL) {
+    output_message = tr("Invalid tree data.");
+    qDebug("Root item for merging two models is null.");
     return false;
   }
 
-  return false;
+  QStack<FeedsModelRootItem*> original_parents; original_parents.push(m_rootItem);
+  QStack<FeedsModelRootItem*> new_parents; new_parents.push(root_item);
+  bool some_feed_category_error = false;
+
+  // We are definitely about to add some new items into the model.
+  emit layoutAboutToBeChanged();
+
+  // Iterate all new items we would like to merge into current model.
+  while (!new_parents.isEmpty()) {
+    FeedsModelRootItem *target_parent = original_parents.pop();
+    FeedsModelRootItem *source_parent = new_parents.pop();
+
+    foreach (FeedsModelRootItem *source_item, source_parent->childItems()) {
+      if (source_item->kind() == FeedsModelRootItem::Category) {
+        FeedsModelCategory *source_category = static_cast<FeedsModelCategory*>(source_item);
+        FeedsModelCategory *new_category = new FeedsModelCategory(source_category);
+
+        // Process all children of this category.
+        original_parents.push(new_category);
+        new_parents.push(source_category);
+
+        // Add category to model.
+        new_category->clearChildren();
+        addCategory(new_category, target_parent);
+      }
+      else if (source_item->kind() == FeedsModelRootItem::Feed) {
+        FeedsModelFeed *source_feed = static_cast<FeedsModelFeed*>(source_item);
+        // TODO: dodělat kopirovaci konstruktor pořádně.
+        FeedsModelFeed *new_feed = new FeedsModelFeed(*source_feed);
+
+        // Append this feed and end this iteration.
+        addFeed(new_feed, target_parent);
+      }
+    }
+  }
+
+  // Changes are done now. Finalize the new model.
+  emit layoutChanged();
+
+  return true;
 }
 
 bool FeedsModel::doesItemContainSameItem(FeedsModelRootItem *parent, FeedsModelRootItem *item) {
diff --git a/src/core/feedsmodelfeed.cpp b/src/core/feedsmodelfeed.cpp
index 0e4c01044..629ecbb81 100755
--- a/src/core/feedsmodelfeed.cpp
+++ b/src/core/feedsmodelfeed.cpp
@@ -48,6 +48,24 @@ FeedsModelFeed::FeedsModelFeed(FeedsModelRootItem *parent_item)
   m_kind = FeedsModelRootItem::Feed;
 }
 
+FeedsModelFeed::FeedsModelFeed(const FeedsModelFeed &other)
+  : FeedsModelRootItem(NULL), m_totalCount(0), m_unreadCount(0) {
+  m_status = other.status();
+  m_type = other.type();
+  m_autoUpdateType = other.autoUpdateType();
+  m_autoUpdateInitialInterval = other.autoUpdateInitialInterval();
+  m_encoding = other.encoding();
+  m_url = other.url();
+  m_kind = other.kind();
+  m_title = other.title();
+  m_id = other.id();
+  m_icon = other.icon();
+  m_childItems = other.childItems();
+  m_parentItem = other.parent();
+  m_creationDate = other.creationDate();
+  m_description = other.description();
+}
+
 FeedsModelFeed::~FeedsModelFeed() {
   qDebug("Destroying FeedsModelFeed instance.");
 }
diff --git a/src/core/feedsmodelfeed.h b/src/core/feedsmodelfeed.h
index 26a89147c..a676c8a0c 100755
--- a/src/core/feedsmodelfeed.h
+++ b/src/core/feedsmodelfeed.h
@@ -63,6 +63,7 @@ class FeedsModelFeed : public FeedsModelRootItem {
 
     // Constructors and destructors.
     explicit FeedsModelFeed(FeedsModelRootItem *parent_item = NULL);
+    explicit FeedsModelFeed(const FeedsModelFeed &other);
     virtual ~FeedsModelFeed();
 
     // Returns 0, feeds have no children.