> ## Documentation Index
> Fetch the complete documentation index at: https://docs.autheo.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Buying and trading THEO on Hydrex
> Step-by-step guide to buying and selling THEO on Hydrex, a decentralized exchange built on Base network.
[Hydrex](https://www.hydrex.fi/) is a decentralized exchange (DEX) built on Base network where THEO can be bought, sold, and traded. Because Hydrex runs on Base rather than Autheo Mainnet, you'll need THEO (or funds to buy THEO) available on Base network before you can trade.
If you already hold THEO on Autheo Mainnet — for example, validator rewards, staking rewards, or Node Sale tokens — bridge it to Base first. See [Bridging THEO from Autheo Mainnet to Base](/web-apps/bridge/bridging-theo-to-base).
## Requirements
| Requirement | Details |
| ----------- | ------------------------------------------------------------------------ |
| Wallet | An EVM-compatible wallet (e.g. MetaMask, Keplr, Coinbase Wallet, Ledger) |
| Gas | ETH on Base network, to pay transaction fees |
## 1. Get ETH on Base for gas
Every buy, sell, or trade on Hydrex requires ETH on Base network to pay gas. You can acquire it by:
* Buying ETH (Base) directly on a CEX or DEX
* Swapping into it using your wallet's built-in swap feature (e.g. MetaMask Swap)
* Bridging ETH from another network to Base via [Base Bridge](https://bridge.base.org/) or a third-party cross-chain bridge (e.g. Superbridge, Brid.gg)
## 2. Add THEO as a custom token on Base
The first time you interact with THEO on Base, add it as a custom token in your wallet. The steps below use MetaMask; the process is similar for other EVM wallets.
In your wallet, go to **Tokens** and select **Base network**.
Click the three-dot menu and choose **Manage tokens**.
Click **Add a custom token**.
Make sure the **Network** is set to **Base**, then enter the token contract address:
```
0xebE516a20238F79DC20b07eaD6768e08891Ed309
```
Click **Add token**.
Always verify this contract address against this page or [docs.autheo.com](https://docs.autheo.com) directly before adding it or entering it into a swap. Never trust a contract address sent to you in a message or DM.
THEO now appears in your wallet's token list for Base network.
## 3. Connect to Hydrex
Navigate to [https://www.hydrex.fi/](https://www.hydrex.fi/).
Click **Connect**.
Choose the wallet you want to use.
After choosing the desired wallet (e.g. MetaMask), click **Connect**.
Your wallet address is displayed once the connection succeeds.
Click **Trade**, or go directly to [hydrex.fi/swap](https://www.hydrex.fi/swap).
## 4. Buy THEO
In the **Sell** field, choose the token you want to use to buy THEO (e.g. USDC).
In the **Buy** field, choose THEO. Verify the contract address by copying it (using the overlapping-squares copy icon) and checking it matches `0xebE516a20238F79DC20b07eaD6768e08891Ed309`.
Enter the amount you want to buy, then confirm the transaction. This triggers a wallet pop-up for signing — approve it to complete the purchase.
## 5. Sell or trade THEO
In the **Sell** field, choose THEO.
In the **Buy** field, choose the token you want to receive (e.g. USDC).
Enter the amount you want to sell, then confirm the transaction. This triggers a wallet pop-up for signing — approve it to complete the trade.
Hydrex is an independent, third-party decentralized exchange built on Base and is not owned or operated by Autheo. Trading on Hydrex is subject to Hydrex's own terms — review [Hydrex's Terms of Service](https://www.hydrex.fi/terms) before trading.