diff --git a/packages/light.js/src/index.ts b/packages/light.js/src/index.ts
index 1870a7d1..d6f52c3f 100644
--- a/packages/light.js/src/index.ts
+++ b/packages/light.js/src/index.ts
@@ -17,6 +17,7 @@ export const {
   accounts$,
   accountsInfo$,
   balanceOf$,
+  transactionCountOf$,
   blockNumber$,
   chainName$,
   defaultAccount$,
diff --git a/packages/light.js/src/rpc/eth.ts b/packages/light.js/src/rpc/eth.ts
index 9e982f4f..efefb4d4 100644
--- a/packages/light.js/src/rpc/eth.ts
+++ b/packages/light.js/src/rpc/eth.ts
@@ -45,6 +45,22 @@ export function balanceOf$ (address: Address, options?: RpcObservableOptions) {
   })(options)(address);
 }
 
+/**
+ * Get the transaction count of a given account. Calls `eth_getTransactionCount`
+ *
+ * @param address - Address of the account whose transaction count we want to query.
+ * @param options - Options to pass to {@link RpcObservableOptions}.
+ * @return - An Observable containing the transaction count.
+ */
+export function transactionCountOf$ (address: Address, options?: RpcObservableOptions) {
+  return createRpc$<any, number | Symbol>({
+    calls: ['eth_getTransactionCount'],
+    frequency: [frequency.onEveryBlock$, frequency.onStartup$],
+    name: 'transactionCountOf$',
+    pipes: api => [switchMapPromise(() => api.eth.getTransactionCount(address).then(Number))]
+  })(options)(address);
+}
+
 /**
  * Get the default account managed by the light client.
  *
diff --git a/packages/light.js/src/utils/testHelpers/mockApi.ts b/packages/light.js/src/utils/testHelpers/mockApi.ts
index 79583d36..341780c3 100644
--- a/packages/light.js/src/utils/testHelpers/mockApi.ts
+++ b/packages/light.js/src/utils/testHelpers/mockApi.ts
@@ -22,7 +22,7 @@ export class MockProvider extends EventEmitter {
 
 // List of JSONRPCs we want to mock
 const listOfMockRps: { [index: string]: string[] } = {
-  eth: ['accounts', 'blockNumber', 'getBalance', 'newHeads', 'syncing'],
+  eth: ['accounts', 'blockNumber', 'getBalance', 'getTransactionCount', 'newHeads', 'syncing'],
   fake: ['method'],
   net: ['peerCount'],
   parity: ['accountsInfo', 'chain', 'postTransaction']