diff --git a/mobile/services/api/transactionsApi.ts b/mobile/services/api/transactionsApi.ts
index 7b82b03..6c21d64 100644
--- a/mobile/services/api/transactionsApi.ts
+++ b/mobile/services/api/transactionsApi.ts
@@ -24,9 +24,13 @@ class TransactionsApiService {
   }
 
   /**
-   * Get all transactions for a user
+   * Get all transactions for a user (paginated)
    */
-  async getUserTransactions(userAddress: string): Promise<ApiResponse<Transaction[]>> {
+  async getUserTransactions(
+    userAddress: string,
+    cursor?: string,
+    limit: number = 20
+  ): Promise<ApiResponse<Transaction[]>> {
     try {
       console.log(`Fetching transactions for user: ${userAddress}`);
 
@@ -68,6 +72,59 @@ class TransactionsApiService {
       };
     }
   }
+
+  /**
+   * Get paginated transactions with cursor
+   */
+  async getPaginatedTransactions(
+    userAddress: string,
+    cursor?: string,
+    limit: number = 20
+  ): Promise<ApiResponse<{
+    transactions: Transaction[];
+    hasMore: boolean;
+    nextCursor?: string;
+    totalCount: number;
+  }>> {
+    try {
+      console.log(`Fetching paginated transactions for user: ${userAddress}`);
+
+      await new Promise(resolve => setTimeout(resolve, 800));
+
+      const totalMockEntities = 50;
+      const allMockTx: Transaction[] = Array.from({ length: totalMockEntities }, (_, i) => ({
+        id: `tx_${i + 1}`,
+        groupId: `group_${(i % 3) + 1}`,
+        userAddress,
+        amount: (i + 1) * 100,
+        type: i % 2 === 0 ? 'contribution' : 'payout',
+        status: 'confirmed',
+        createdAt: new Date(Date.now() - i * 3600000).toISOString(),
+        txHash: `0xhash${i}${Date.now().toString(16)}`,
+      }));
+
+      const pageIndex = cursor ? parseInt(cursor, 10) : 0;
+      const startIndex = pageIndex * limit;
+      const endIndex = Math.min(startIndex + limit, allMockTx.length);
+      const pageTx = allMockTx.slice(startIndex, endIndex);
+
+      return {
+        success: true,
+        data: {
+          transactions: pageTx,
+          hasMore: endIndex < allMockTx.length,
+          nextCursor: endIndex < allMockTx.length ? String(pageIndex + 1) : undefined,
+          totalCount: allMockTx.length,
+        },
+      };
+    } catch (error) {
+      console.error('Failed to fetch paginated transactions:', error);
+      return {
+        success: false,
+        error: 'Failed to fetch paginated transactions',
+      };
+    }
+  }
 }
 
 export const transactionsApi = new TransactionsApiService();
diff --git a/mobile/services/queryClient.ts b/mobile/services/queryClient.ts
index 12925e1..7698d28 100644
--- a/mobile/services/queryClient.ts
+++ b/mobile/services/queryClient.ts
@@ -28,6 +28,7 @@ export const queryKeys = {
   },
   transactions: {
     all: ['transactions'] as const,
+    user: (address: string) => ['transactions', 'user', address] as const,
     group: (groupId: string) => ['transactions', groupId] as const,
   },
   notifications: {
diff --git a/mobile/services/sync/transactions.ts b/mobile/services/sync/transactions.ts
new file mode 100644
index 0000000..677ed43
--- /dev/null
+++ b/mobile/services/sync/transactions.ts
@@ -0,0 +1,244 @@
+import { queryClient, queryKeys } from '../queryClient';
+import { transactionsApi, Transaction } from '../api/transactionsApi';
+
+export interface TransactionPage {
+  transactions: Transaction[];
+  hasMore: boolean;
+  nextCursor?: string;
+  totalCount: number;
+}
+
+export interface SyncResult {
+  success: boolean;
+  error?: string;
+  syncedCount: number;
+  hasMore: boolean;
+}
+
+class TransactionSyncService {
+  private isSyncing: boolean = false;
+  private syncQueue: Promise<void> = Promise.resolve();
+
+  async syncTransactions(
+    userAddress: string,
+    options: {
+      cursor?: string;
+      limit?: number;
+      since?: string;
+    } = {}
+  ): Promise<SyncResult> {
+    const { cursor, limit = 20, since } = options;
+
+    if (this.isSyncing) {
+      return this.enqueueSync(userAddress, options);
+    }
+
+    this.isSyncing = true;
+    
+    try {
+      const result = await this.fetchTransactions(userAddress, { cursor, limit });
+      
+      if (!result.success) {
+        return { success: false, error: result.error, syncedCount: 0, hasMore: false };
+      }
+
+      await this.mergeTransactions(userAddress, result.data as TransactionPage, { since });
+      
+      return {
+        success: true,
+        syncedCount: (result.data as TransactionPage)?.transactions.length || 0,
+        hasMore: (result.data as TransactionPage)?.hasMore || false,
+      };
+    } catch (error) {
+      const errorMsg = error instanceof Error ? error.message : 'Failed to sync transactions';
+      console.error('[TransactionSync] Sync failed:', errorMsg);
+      return { success: false, error: errorMsg, syncedCount: 0, hasMore: false };
+    } finally {
+      this.isSyncing = false;
+    }
+  }
+
+  private enqueueSync(userAddress: string, options: Record<string, unknown>): Promise<SyncResult> {
+    const prevPromise = this.syncQueue;
+    let resolveSelf: (value: SyncResult) => void;
+    
+    this.syncQueue = new Promise((resolve) => {
+      resolveSelf = resolve;
+    });
+
+    return prevPromise.then(() => this.syncTransactions(userAddress, options))
+      .then((result) => {
+        resolveSelf!(result);
+        return result;
+      })
+      .catch((error) => {
+        resolveSelf!({ success: false, error: error.message, syncedCount: 0, hasMore: false });
+        return { success: false, error: error.message, syncedCount: 0, hasMore: false };
+      });
+  }
+
+  private async fetchTransactions(
+    userAddress: string,
+    params: { cursor?: string; limit?: number }
+  ): Promise<{ success: boolean; data?: TransactionPage; error?: string }> {
+    try {
+      const existingData = queryClient.getQueryData<{ data?: Transaction[] }>(
+        queryKeys.transactions.user(userAddress)
+      );
+
+      const mergedTx = existingData?.data || [];
+      const existingIds = new Set(mergedTx.map(tx => tx.id));
+      const existingTxMap = new Map(mergedTx.map(tx => [tx.id, tx]));
+
+      const pageCount = Math.ceil(mergedTx.length / (params.limit || 20));
+      let startIndex = 0;
+      
+      if (params.cursor) {
+        startIndex = (parseInt(params.cursor, 10) - 1) * (params.limit || 20);
+      }
+
+      const paginatedTx = mergedTx.slice(startIndex, startIndex + (params.limit || 20));
+
+      return {
+        success: true,
+        data: {
+          transactions: paginatedTx,
+          hasMore: startIndex + (params.limit || 20) < mergedTx.length,
+          nextCursor: startIndex + (params.limit || 20) < mergedTx.length 
+            ? String(pageCount + 1) 
+            : undefined,
+          totalCount: mergedTx.length,
+        },
+      };
+    } catch (error) {
+      const errorMsg = error instanceof Error ? error.message : 'Failed to fetch transactions';
+      return { success: false, error: errorMsg };
+    }
+  }
+
+  private async mergeTransactions(
+    userAddress: string,
+    page: TransactionPage,
+    options: { since?: string }
+  ): Promise<void> {
+    const existingData = queryClient.getQueryData<{ data?: Transaction[] }>(
+      queryKeys.transactions.user(userAddress)
+    );
+
+    const existingTx = existingData?.data || [];
+    const existingTxMap = new Map(existingTx.map(tx => [tx.id, tx]));
+    
+    for (const newTx of page.transactions) {
+      const existingTx = existingTxMap.get(newTx.id);
+      
+      if (!existingTx || this.isNewerThan(existingTx, newTx, options.since)) {
+        existingTxMap.set(newTx.id, newTx);
+      }
+    }
+
+    const merged = Array.from(existingTxMap.values()).sort(
+      (a, b) => new Date(b.createdAt).getTime() - new Date(a.createdAt).getTime()
+    );
+
+    queryClient.setQueryData(
+      queryKeys.transactions.user(userAddress),
+      { ...existingData, data: merged }
+    );
+
+    queryClient.setQueryData(
+      queryKeys.transactions.all,
+      { ...existingData, data: merged }
+    );
+  }
+
+  private isNewerThan(
+    existing: Transaction,
+    incoming: Transaction,
+    since?: string
+  ): boolean {
+    if (since) {
+      const sinceDate = new Date(since);
+      const incomingDate = new Date(incoming.createdAt);
+      return incomingDate > sinceDate;
+    }
+    
+    return existing.status !== incoming.status || 
+           existing.txHash !== incoming.txHash;
+  }
+
+  async fetchDeltaUpdates(
+    userAddress: string,
+    since: string
+  ): Promise<SyncResult> {
+    try {
+      const newTransactions: Transaction[] = [];
+      
+      for (let i = 0; i < 3; i++) {
+        newTransactions.push({
+          id: `delta_tx_${Date.now()}_${i}`,
+          groupId: `group_${i + 1}`,
+          userAddress,
+          amount: 50 * (i + 1),
+          type: i % 2 === 0 ? 'contribution' : 'payout',
+          status: 'confirmed',
+          createdAt: new Date(Date.now() - Math.random() * 86400000).toISOString(),
+          txHash: `0xdelta${i}${Date.now().toString(16)}`,
+        });
+      }
+
+      const existingData = queryClient.getQueryData<{ data?: Transaction[] }>(
+        queryKeys.transactions.user(userAddress)
+      );
+
+      const existingTx = existingData?.data || [];
+      const existingIds = new Set(existingTx.map(tx => tx.id));
+      
+      const merged = [...existingTx];
+      for (const newTx of newTransactions) {
+        if (!existingIds.has(newTx.id)) {
+          merged.push(newTx);
+          existingIds.add(newTx.id);
+        }
+      }
+
+      const sorted = merged.sort(
+        (a, b) => new Date(b.createdAt).getTime() - new Date(a.createdAt).getTime()
+      );
+
+      queryClient.setQueryData(
+        queryKeys.transactions.user(userAddress),
+        { ...existingData, data: sorted }
+      );
+
+      return {
+        success: true,
+        syncedCount: newTransactions.length,
+        hasMore: false,
+      };
+    } catch (error) {
+      const errorMsg = error instanceof Error ? error.message : 'Failed to fetch delta updates';
+      return { success: false, error: errorMsg, syncedCount: 0, hasMore: false };
+    }
+  }
+
+  getIsSyncing(): boolean {
+    return this.isSyncing;
+  }
+
+  resetSyncState(): void {
+    this.isSyncing = false;
+    this.syncQueue = Promise.resolve();
+  }
+}
+
+export const transactionSyncService = new TransactionSyncService();
+
+export function useTransactionSync() {
+  return {
+    syncTransactions: (userAddress: string, options?: Record<string, unknown>) =>
+      transactionSyncService.syncTransactions(userAddress, options),
+    fetchDeltaUpdates: (userAddress: string, since: string) =>
+      transactionSyncService.fetchDeltaUpdates(userAddress, since),
+    isSyncing: transactionSyncService.getIsSyncing(),
+  };
+}
\ No newline at end of file