diff --git a/src/popup/locales/en.json b/src/popup/locales/en.json
index e4e797bcf..af4d4f4c2 100644
--- a/src/popup/locales/en.json
+++ b/src/popup/locales/en.json
@@ -1238,6 +1238,7 @@
     "required": "This field is required",
     "url": "Invalid URL",
     "address": "Enter valid blockchain address or .chain name",
+    "numeric": "The value should be a number",
     "name": "Enter valid .chain name",
     "nameRegisteredAddress": "Invalid address or .chain name",
     "nameUnregistered": "This name has already been registered.",
@@ -1250,7 +1251,6 @@
     "enoughAeSigner": "Insufficient balance on your signing account to propose a transaction",
     "maxLength": "The value should be no longer than {0} characters",
     "maxValue": "This field must be {0} or less",
-    "hexFormat": "The value should be in hex format",
     "maxRedeem": "Maximum redeemable amount is {0} AE.",
     "maxValueVault": "Amount is exceeding the vault's balance: {0}",
     "notToken": "Tokens are currently not allowed, please switch to AE",
diff --git a/src/popup/plugins/veeValidate.ts b/src/popup/plugins/veeValidate.ts
index eff959dcb..87b5442f4 100644
--- a/src/popup/plugins/veeValidate.ts
+++ b/src/popup/plugins/veeValidate.ts
@@ -1,5 +1,5 @@
 import { defineRule } from 'vee-validate';
-import { required } from '@vee-validate/rules';
+import { numeric, required } from '@vee-validate/rules';
 import BigNumber from 'bignumber.js';
 import { debounce } from 'lodash-es';
 import { isAddressValid, isNameValid } from '@aeternity/aepp-sdk';
@@ -32,6 +32,11 @@ defineRule(
   (value: string) => !value || isUrlValid(value) || tg('validation.url'),
 );
 
+defineRule(
+  'numeric',
+  (value: string) => numeric(value) || tg('validation.numeric'),
+);
+
 defineRule(
   'account',
   (value: string) => isAddressValid(value) || isNameValid(value) || tg('validation.address'),
@@ -109,18 +114,6 @@ defineRule(
   },
 );
 
-defineRule(
-  'is_hex_format',
-  (value: string) => (
-    (
-      value?.toString()?.startsWith('0x')
-      && value.length >= 3
-      && parseInt(value.slice(2), 16).toString(16) === value.slice(2).toLowerCase()
-    )
-    || tg('validation.hexFormat')
-  ),
-);
-
 export default () => {
   const { balance, updateBalances } = useBalances();
   const { currencyRates } = useCurrencies({ pollingDisabled: true });
diff --git a/src/protocols/ethereum/config.ts b/src/protocols/ethereum/config.ts
index 8d6e7a933..8bcb0e330 100644
--- a/src/protocols/ethereum/config.ts
+++ b/src/protocols/ethereum/config.ts
@@ -14,6 +14,7 @@ export const ETH_COIN_PRECISION = 18; // Amount of decimals
 
 export const ETH_COINGECKO_COIN_ID = 'ethereum';
 export const ETH_GAS_LIMIT = 21000;
+export const ETH_CHAIN_NAMESPACE = 'eip155';
 
 /**
  * Estimated time we need to wait for the middleware (etherscan) to sync it's state
@@ -70,11 +71,11 @@ export const ETH_SAFE_CONFIRMATION_COUNT = 12;
 export const ETH_NETWORK_DEFAULT_SETTINGS: IDefaultNetworkTypeData<IEthNetworkSettings> = {
   [NETWORK_TYPE_MAINNET]: {
     nodeUrl: 'https://ethereum-rpc.publicnode.com', // TODO replace temp values - use our own node
-    chainId: '0x1',
+    chainId: '1',
   },
   [NETWORK_TYPE_TESTNET]: {
     nodeUrl: 'https://ethereum-sepolia-rpc.publicnode.com', // TODO replace temp values - use our own node
-    chainId: '0xaa36a7',
+    chainId: '11155111',
   },
 };
 
diff --git a/src/protocols/ethereum/libs/EthereumAdapter.ts b/src/protocols/ethereum/libs/EthereumAdapter.ts
index a9e5a57fc..0ee26d6f2 100644
--- a/src/protocols/ethereum/libs/EthereumAdapter.ts
+++ b/src/protocols/ethereum/libs/EthereumAdapter.ts
@@ -41,7 +41,7 @@ import type {
   NetworkTypeDefault,
 } from '@/types';
 import { PROTOCOLS } from '@/constants';
-import { getLastNotEmptyAccountIndex } from '@/utils';
+import { getLastNotEmptyAccountIndex, toHex } from '@/utils';
 import Logger from '@/lib/logger';
 import { BaseProtocolAdapter } from '@/protocols/BaseProtocolAdapter';
 import { tg } from '@/popup/plugins/i18n';
@@ -100,7 +100,7 @@ export class EthereumAdapter extends BaseProtocolAdapter {
       defaultValue: ETH_NETWORK_DEFAULT_ENV_SETTINGS.chainId,
       validationRules: {
         url: false,
-        is_hex_format: true,
+        numeric: true,
       },
       getPlaceholder: () => tg('pages.network.chainIdPlaceholder'),
       getLabel: () => tg('pages.network.chainIdLabel'),
@@ -296,7 +296,7 @@ export class EthereumAdapter extends BaseProtocolAdapter {
 
     // All values are in wei
     const txData: FeeMarketEIP1559TxData = {
-      chainId,
+      chainId: toHex(chainId),
       nonce,
       to: contractId,
       data: contract.methods.transfer(recipient, hexAmount).encodeABI(),
@@ -435,7 +435,7 @@ export class EthereumAdapter extends BaseProtocolAdapter {
 
     // All values are in wei
     const txData: FeeMarketEIP1559TxData = {
-      chainId,
+      chainId: toHex(chainId),
       nonce,
       to: recipient,
       value: hexAmount,
diff --git a/src/protocols/ethereum/types.ts b/src/protocols/ethereum/types.ts
index 266576c9c..705d0e28c 100644
--- a/src/protocols/ethereum/types.ts
+++ b/src/protocols/ethereum/types.ts
@@ -3,7 +3,8 @@ import { INetworkProtocolSettings } from '@/types';
 /**
  * Settings specific to this protocol.
  */
-export type EthNetworkProtocolSettings = 'chainId';
+export type EthNetworkProtocolSettings =
+  | 'chainId'; // ref: https://docs.simplehash.com/reference/supported-chains-testnets
 
 /**
  * Settings that are not editable by the user but are assigned to specific network types.
diff --git a/src/utils/common.ts b/src/utils/common.ts
index f7c1253a8..39ab1023d 100644
--- a/src/utils/common.ts
+++ b/src/utils/common.ts
@@ -392,6 +392,10 @@ export function splitAddress(address: string | null): string {
     : '';
 }
 
+export function toHex(value: string) {
+  return `0x${parseInt(value, 10).toString(16)}`;
+}
+
 export function toShiftedBigNumber(value: number | string, precision: number): BigNumberPublic {
   return new BigNumber(value).shiftedBy(precision);
 }