eth_getTransactionByBlockHashAndIndex

eth_getTransactionByBlockHashAndIndex fetches a single transaction by where it sits, not by what it is. You name a block by its hash and a zero-based position within that block, and Ethereum mainnet (chain ID 1, fees denominated in ETH) returns the full transaction object at that slot. The order matters here: a validator fixes the transaction ordering when it seals the block, and that order is exactly what this index walks. It's the same transaction object you'd get from eth_getTransactionByHash, just addressed positionally. Querying by block hash rather than number means you're pinned to one specific block even across a reorg. Send the call to https://ethereum.therpc.io/YOUR_API_KEY.

Use cases

• Walk a block's transactions in order by incrementing the index from 0x0 until you hit null, when you already have the block hash but not the individual tx hashes.
• Pull the first transaction in a block to study ordering — the top slot is where MEV searchers and builders fight to land arbitrage and liquidation bundles.
• Resolve a transaction by its position reference (block hash plus index) when that's how it was cited, instead of needing its hash up front.

Parameters

Response

Example request

1curl https://ethereum.therpc.io/YOUR_API_KEY \
2  -X POST \
3  -H "Content-Type: application/json" \
4  -d '{
5    "jsonrpc": "2.0",
6    "method": "eth_getTransactionByBlockHashAndIndex",
7    "params": [
8        "0x0000000000000000000000000000000000000000000000000000000000000000",
9        "0x0"
10      ],
11    "id": 1
12  }'

Try it live in the Ethereum playground.

Errors & troubleshooting

Common pitfalls

• The index is hex, not decimal. The first transaction is "0x0", the eleventh is "0xa" — passing a bare 0 or a decimal 10 will misfire.
• Run the index past the block's last transaction and you get null, not an error. Pair this with eth_getBlockTransactionCountByNumber, or just treat null as your stop condition when enumerating.

Supported networks

• Mainnet — Chain ID: 1
• Sepolia — Chain ID: 11155111

See also

• eth_getTransactionByHash
• eth_getTransactionByBlockNumberAndIndex
• eth_getBlockByHash
• eth_getTransactionReceipt

1curl https://ethereum.therpc.io/YOUR_API_KEY \
2  -X POST \
3  -H 'Content-Type: application/json' \
4  -d '{"jsonrpc":"2.0","id":1,"method":"eth_getTransactionByBlockHashAndIndex","params":["0x0000000000000000000000000000000000000000000000000000000000000000","0x0"]}'