diff --git a/execution_chain/constants.nim b/execution_chain/constants.nim
index a6d0d3762..b6759a608 100644
--- a/execution_chain/constants.nim
+++ b/execution_chain/constants.nim
@@ -107,4 +107,8 @@ const
   HISTORY_STORAGE_ADDRESS* = address"0x0000F90827F1C53a10cb7A02335B175320002935"
   WITHDRAWAL_REQUEST_PREDEPLOY_ADDRESS* = address"0x00000961Ef480Eb55e80D19ad83579A64c007002"
   CONSOLIDATION_REQUEST_PREDEPLOY_ADDRESS* = address"0x0000BBdDc7CE488642fb579F8B00f3a590007251"
+
+  MAX_BLOCK_SIZE* = 10_485_760  # 10 MiB
+  SAFETY_MARGIN* = 2_097_152  # 2 MiB
+  MAX_RLP_BLOCK_SIZE* = MAX_BLOCK_SIZE - SAFETY_MARGIN
 # End
diff --git a/execution_chain/core/executor/process_block.nim b/execution_chain/core/executor/process_block.nim
index fe4f4cc99..73737ac8a 100644
--- a/execution_chain/core/executor/process_block.nim
+++ b/execution_chain/core/executor/process_block.nim
@@ -12,6 +12,7 @@
 
 import
   ../../common/common,
+  ../../constants,
   ../../utils/utils,
   ../../constants,
   ../../db/ledger,
@@ -118,6 +119,10 @@ proc procBlkPreamble(
     if blk.transactions.calcTxRoot != header.txRoot:
       return err("Mismatched txRoot")
 
+  if com.isOsakaOrLater(header.timestamp):
+    if rlp.getEncodedLength(blk) > MAX_RLP_BLOCK_SIZE:
+      return err("Post-Osaka block exceeded MAX_RLP_BLOCK_SIZE")
+
   if com.isPragueOrLater(header.timestamp):
     if header.requestsHash.isNone:
       return err("Post-Prague block header must have requestsHash")
diff --git a/execution_chain/core/tx_pool.nim b/execution_chain/core/tx_pool.nim
index ac2403cc4..c1f3bd6fd 100644
--- a/execution_chain/core/tx_pool.nim
+++ b/execution_chain/core/tx_pool.nim
@@ -160,9 +160,13 @@ proc assembleBlock*(
     blobsBundle = BlobsBundle(
       wrapperVersion: getWrapperVersion(com, blk.header.timestamp)
     )
+    currentRlpSize = rlp.getEncodedLength(blk.header) + rlp.getEncodedLength(blk.withdrawals)
 
   for item in pst.packedTxs:
     let tx = item.pooledTx
+    if currentRlpSize > MAX_RLP_BLOCK_SIZE - 7:
+      break
+    currentRlpSize = currentRlpSize + rlp.getEncodedLength(tx.tx)
     blk.txs.add tx.tx
     if tx.blobsBundle != nil:
       doAssert(tx.blobsBundle.wrapperVersion == blobsBundle.wrapperVersion)