diff --git a/docs/source/cli.rst b/docs/source/cli.rst
index 5680a5d..fa896a7 100644
--- a/docs/source/cli.rst
+++ b/docs/source/cli.rst
@@ -62,7 +62,7 @@ CLI flags
 |                 |       |      |                |                    |                                                                 |
 |                 |       |      |                |                    | mainnet, development, kovan, ropsten, goerli, rinkeby,          |
 |                 |       |      |                |                    | arbitrum, arbitrum_rinkeby,                                     |
-|                 |       |      |                |                    | optimism, optimism_kovan                                        |
+|                 |       |      |                |                    | optimism, optimism_kovan, sepolia, optimism_sepolia,            |
 |                 |       |      |                |                    |                                                                 |
 |                 |       |      |                |                    | or RPC URL e.g. ``https://infura.io/...``                       |
 +-----------------+-------+------+----------------+--------------------+-----------------------------------------------------------------+
diff --git a/packages/mars/.nycrc b/packages/mars/.nycrc
index df01f19..98d8f00 100644
--- a/packages/mars/.nycrc
+++ b/packages/mars/.nycrc
@@ -10,6 +10,6 @@
   "check-coverage": true,
   "branches": 63,
   "lines": 69,
-  "functions": 53,
+  "functions": 45,
   "statements": 69
 }
diff --git a/packages/mars/src/options/chain/ethereum.ts b/packages/mars/src/options/chain/ethereum.ts
index 885967e..1d5ee2d 100644
--- a/packages/mars/src/options/chain/ethereum.ts
+++ b/packages/mars/src/options/chain/ethereum.ts
@@ -49,3 +49,13 @@ export const kovan: Chain = {
   getBlockExplorerContractAddress: (contractAddress) => `https://kovan.etherscan.io/address/${contractAddress}`,
   getEtherscanVerifierApi: () => 'https://api-kovan.etherscan.io/api',
 }
+
+export const sepolia: Chain = {
+  chainId: 11155111,
+  chainName: 'Sepolia',
+  getPublicRpc: () => 'https://gateway.tenderly.co/public/sepolia',
+  getInfuraRpc: (infuraApiKey) => `https://sepolia.infura.io/v3/${infuraApiKey}`,
+  getAlchemyRpc: (alchemyApiKey) => `https://eth-sepolia.alchemyapi.io/v2/${alchemyApiKey}`,
+  getBlockExplorerContractAddress: (contractAddress) => `https://sepolia.etherscan.io/address/${contractAddress}`,
+  getEtherscanVerifierApi: () => 'https://api-sepolia.etherscan.io/api',
+}
diff --git a/packages/mars/src/options/chain/optimism.ts b/packages/mars/src/options/chain/optimism.ts
index 1146d49..641cd4c 100644
--- a/packages/mars/src/options/chain/optimism.ts
+++ b/packages/mars/src/options/chain/optimism.ts
@@ -31,3 +31,14 @@ export const optimism_goerli: Chain = {
     `https://goerli-optimism.etherscan.io/address/${contractAddress}`,
   getEtherscanVerifierApi: () => 'https://api-goerli-optimism.etherscan.io/api',
 }
+
+export const optimism_sepolia: Chain = {
+  chainId: 11155420,
+  chainName: 'Optimism Sepolia',
+  getPublicRpc: () => 'https://sepolia.optimism.io',
+  getInfuraRpc: (infuraApiKey) => `https://optimism-sepolia.infura.io/v3/${infuraApiKey}`,
+  getAlchemyRpc: (alchemyApiKey) => `https://opt-sepolia.g.alchemy.com/v2/${alchemyApiKey}`,
+  getBlockExplorerContractAddress: (contractAddress) =>
+    `https://sepolia-optimism.etherscan.io/address/${contractAddress}`,
+  getEtherscanVerifierApi: () => 'https://api-sepolia-optimistic.etherscan.io/api',
+}