diff --git a/README.md b/README.md
index b0d4429..39ac9f9 100644
--- a/README.md
+++ b/README.md
@@ -129,6 +129,7 @@ $ make test
 * [`eth_protocolVersion`](https://eth.wiki/json-rpc/API#eth_protocolversion)
 * [`eth_syncing`](https://eth.wiki/json-rpc/API#eth_syncing)
 * [`eth_coinbase`](https://eth.wiki/json-rpc/API#eth_coinbase)
+* [`eth_chainId`](https://eth.wiki/json-rpc/API#eth_chainId)
 * [`eth_mining`](https://eth.wiki/json-rpc/API#eth_mining)
 * [`eth_hashrate`](https://eth.wiki/json-rpc/API#eth_hashrate)
 * [`eth_gasPrice`](https://eth.wiki/json-rpc/API#eth_gasprice)
diff --git a/lib/ethereumex/client/base_client.ex b/lib/ethereumex/client/base_client.ex
index 6d275c0..dc9f14b 100644
--- a/lib/ethereumex/client/base_client.ex
+++ b/lib/ethereumex/client/base_client.ex
@@ -51,6 +51,11 @@ defmodule Ethereumex.Client.BaseClient do
         request("eth_syncing", [], opts)
       end
 
+      @impl true
+      def eth_chain_id(opts \\ []) do
+        request("eth_chainId", [], opts)
+      end
+
       @impl true
       def eth_coinbase(opts \\ []) do
         request("eth_coinbase", [], opts)
diff --git a/lib/ethereumex/client/behaviour.ex b/lib/ethereumex/client/behaviour.ex
index 5919ab9..1c93e3e 100644
--- a/lib/ethereumex/client/behaviour.ex
+++ b/lib/ethereumex/client/behaviour.ex
@@ -11,6 +11,7 @@ defmodule Ethereumex.Client.Behaviour do
   @callback net_listening(keyword()) :: {:ok, boolean()} | error
   @callback eth_protocol_version(keyword()) :: {:ok, binary()} | error
   @callback eth_syncing(keyword()) :: {:ok, map() | boolean()} | error
+  @callback eth_chain_id(keyword()) :: {:ok, binary()} | error
   @callback eth_coinbase(keyword()) :: {:ok, binary()} | error
   @callback eth_mining(keyword()) :: {:ok, boolean()} | error
   @callback eth_hashrate(keyword()) :: {:ok, binary()} | error
diff --git a/test/ethereumex/client/base_client_test.exs b/test/ethereumex/client/base_client_test.exs
index dcaf1aa..5122a8f 100644
--- a/test/ethereumex/client/base_client_test.exs
+++ b/test/ethereumex/client/base_client_test.exs
@@ -92,6 +92,7 @@ defmodule Ethereumex.Client.BaseClientTest do
   test ".eth_protocol_version/0", do: Helpers.check("eth_protocol_version")
   test ".eth_syncing/0", do: Helpers.check("eth_syncing")
   test ".eth_coinbase/0", do: Helpers.check("eth_coinbase")
+  test ".eth_chain_id/0", do: Helpers.check("eth_chain_id")
   test ".eth_mining/0", do: Helpers.check("eth_mining")
   test ".eth_hashrate/0", do: Helpers.check("eth_hashrate")
   test ".eth_gas_price/0", do: Helpers.check("eth_gas_price")
diff --git a/test/ethereumex/http_client_test.exs b/test/ethereumex/http_client_test.exs
index 9b37f43..ed4dd5a 100644
--- a/test/ethereumex/http_client_test.exs
+++ b/test/ethereumex/http_client_test.exs
@@ -68,6 +68,15 @@ defmodule Ethereumex.HttpClientTest do
     end
   end
 
+  @tag :eth
+  describe "HttpClient.eth_chain_id/1" do
+    test "returns chain id of the RPC serveer" do
+      result = HttpClient.eth_chain_id()
+
+      {:ok, <<_::binary>>} = result
+    end
+  end
+
   @tag :eth
   describe "HttpClient.eth_coinbase/1" do
     test "returns coinbase address" do
diff --git a/test/ethereumex/ipc_client_test.exs b/test/ethereumex/ipc_client_test.exs
index 65f6df9..153f917 100644
--- a/test/ethereumex/ipc_client_test.exs
+++ b/test/ethereumex/ipc_client_test.exs
@@ -79,6 +79,15 @@ defmodule Ethereumex.IpcClientTest do
     end
   end
 
+  @tag :eth
+  describe "IpcClient.eth_chain_id/1" do
+    test "returns chain id of the RPC serveer" do
+      result = IpcClient.eth_chain_id()
+
+      {:ok, <<_::binary>>} = result
+    end
+  end
+
   @tag :eth
   describe "IpcClient.eth_coinbase/1" do
     test "returns coinbase address" do