diff --git a/setup.py b/setup.py
index 0a64307c0..a1cec822c 100644
--- a/setup.py
+++ b/setup.py
@@ -313,11 +313,11 @@ def get_pow_chain_head() -> PowBlock:
     pass
 
 
-def execution_state_transition(execution_state: ExecutionState, execution_payload: ExecutionPayload) -> None:
-    pass
+def verify_execution_state_transition(execution_payload: ExecutionPayload) -> bool:
+    return True
 
 
-def produce_execution_payload(parent_hash: Bytes32) -> ExecutionPayload:
+def produce_execution_payload(parent_hash: Hash32, timestamp: uint64) -> ExecutionPayload:
     pass"""
 
 
diff --git a/specs/merge/beacon-chain.md b/specs/merge/beacon-chain.md
index be79cf5b5..a508cb670 100644
--- a/specs/merge/beacon-chain.md
+++ b/specs/merge/beacon-chain.md
@@ -26,10 +26,10 @@
   - [Misc](#misc)
     - [`is_transition_completed`](#is_transition_completed)
     - [`is_transition_block`](#is_transition_block)
+    - [`compute_time_at_slot`](#compute_time_at_slot)
   - [Block processing](#block-processing)
     - [Execution payload processing](#execution-payload-processing)
-      - [`get_execution_state`](#get_execution_state)
-      - [`execution_state_transition`](#execution_state_transition)
+      - [`verify_execution_state_transition`](#verify_execution_state_transition)
       - [`process_execution_payload`](#process_execution_payload)
 
 <!-- END doctoc generated TOC please keep comment here to allow auto update -->
@@ -98,13 +98,14 @@ The execution payload included in a `BeaconBlockBody`.
 
 ```python
 class ExecutionPayload(Container):
-    block_hash: Bytes32  # Hash of execution block
-    parent_hash: Bytes32
+    block_hash: Hash32  # Hash of execution block
+    parent_hash: Hash32
     coinbase: Bytes20
     state_root: Bytes32
     number: uint64
     gas_limit: uint64
     gas_used: uint64
+    timestamp: uint64
     receipt_root: Bytes32
     logs_bloom: ByteVector[BYTES_PER_LOGS_BLOOM]
     transactions: List[OpaqueTransaction, MAX_APPLICATION_TRANSACTIONS]
@@ -118,13 +119,14 @@ The execution payload header included in a `BeaconState`.
 
 ```python
 class ExecutionPayloadHeader(Container):
-    block_hash: Bytes32  # Hash of execution block
-    parent_hash: Bytes32
+    block_hash: Hash32  # Hash of execution block
+    parent_hash: Hash32
     coinbase: Bytes20
     state_root: Bytes32
     number: uint64
     gas_limit: uint64
     gas_used: uint64
+    timestamp: uint64
     receipt_root: Bytes32
     logs_bloom: ByteVector[BYTES_PER_LOGS_BLOOM]
     transactions_root: Root
@@ -137,17 +139,27 @@ class ExecutionPayloadHeader(Container):
 #### `is_transition_completed`
 
 ```python
-def is_transition_completed(state: BeaconState) -> boolean:
+def is_transition_completed(state: BeaconState) -> bool:
     return state.latest_execution_payload_header != ExecutionPayloadHeader()
 ```
 
 #### `is_transition_block`
 
 ```python
-def is_transition_block(state: BeaconState, block_body: BeaconBlockBody) -> boolean:
+def is_transition_block(state: BeaconState, block_body: BeaconBlockBody) -> bool:
     return not is_transition_completed(state) and block_body.execution_payload != ExecutionPayload()
 ```
 
+#### `compute_time_at_slot`
+
+*Note*: This function is unsafe with respect to overflows and underflows.
+
+```python
+def compute_time_at_slot(state: BeaconState, slot: Slot) -> uint64:
+    slots_since_genesis = slot - GENESIS_SLOT
+    return uint64(state.genesis_time + slots_since_genesis * SECONDS_PER_SLOT)
+```
+
 ### Block processing
 
 ```python
@@ -161,20 +173,11 @@ def process_block(state: BeaconState, block: BeaconBlock) -> None:
 
 #### Execution payload processing
 
-##### `get_execution_state`
+##### `verify_execution_state_transition`
 
-*Note*: `ExecutionState` class is an abstract class representing Ethereum execution state.
-
-Let `get_execution_state(execution_state_root: Bytes32) -> ExecutionState`  be the function that given the root hash returns a copy of Ethereum execution state. 
+Let `verify_execution_state_transition(execution_payload: ExecutionPayload) -> bool` be the function that verifies given `ExecutionPayload` with respect to execution state transition.
 The body of the function is implementation dependent.
 
-##### `execution_state_transition`
-
-Let `execution_state_transition(execution_state: ExecutionState, execution_payload: ExecutionPayload) -> None` be the transition function of Ethereum execution state. 
-The body of the function is implementation dependent.
-
-*Note*: `execution_state_transition` must throw `AssertionError` if either the transition itself or one of the pre or post conditions has failed.
-
 ##### `process_execution_payload`
 
 ```python
@@ -192,8 +195,9 @@ def process_execution_payload(state: BeaconState, body: BeaconBlockBody) -> None
         assert execution_payload.parent_hash == state.latest_execution_payload_header.block_hash
         assert execution_payload.number == state.latest_execution_payload_header.number + 1
 
-    execution_state = get_execution_state(state.latest_execution_payload_header.state_root)
-    execution_state_transition(execution_state, execution_payload)
+    assert execution_payload.timestamp == compute_time_at_slot(state, state.slot)
+
+    assert verify_execution_state_transition(execution_payload)
 
     state.latest_execution_payload_header = ExecutionPayloadHeader(
         block_hash=execution_payload.block_hash,
@@ -203,6 +207,7 @@ def process_execution_payload(state: BeaconState, body: BeaconBlockBody) -> None
         number=execution_payload.number,
         gas_limit=execution_payload.gas_limit,
         gas_used=execution_payload.gas_used,
+        timestamp=execution_payload.timestamp,
         receipt_root=execution_payload.receipt_root,
         logs_bloom=execution_payload.logs_bloom,
         transactions_root=hash_tree_root(execution_payload.transactions),
diff --git a/specs/merge/fork-choice.md b/specs/merge/fork-choice.md
index 647a663c2..34647f45d 100644
--- a/specs/merge/fork-choice.md
+++ b/specs/merge/fork-choice.md
@@ -30,7 +30,7 @@ This is the modification of the fork choice according to the executable beacon c
 
 ```python
 class PowBlock(Container):
-    block_hash: Bytes32
+    block_hash: Hash32
     is_processed: boolean
     is_valid: boolean
     total_difficulty: uint256
@@ -38,7 +38,7 @@ class PowBlock(Container):
 
 #### `get_pow_block`
 
-Let `get_pow_block(hash: Bytes32) -> PowBlock` be the function that given the hash of the PoW block returns its data.
+Let `get_pow_block(block_hash: Hash32) -> PowBlock` be the function that given the hash of the PoW block returns its data.
 
 *Note*: The `eth_getBlockByHash` JSON-RPC method does not distinguish invalid blocks from blocks that haven't been processed yet. Either extending this existing method or implementing a new one is required.
 
@@ -47,7 +47,7 @@ Let `get_pow_block(hash: Bytes32) -> PowBlock` be the function that given the ha
 Used by fork-choice handler, `on_block`.
 
 ```python
-def is_valid_transition_block(block: PowBlock) -> boolean:
+def is_valid_transition_block(block: PowBlock) -> bool:
     is_total_difficulty_reached = block.total_difficulty >= TRANSITION_TOTAL_DIFFICULTY
     return block.is_valid and is_total_difficulty_reached
 ```
@@ -113,4 +113,3 @@ def on_block(store: Store, signed_block: SignedBeaconBlock) -> None:
             if ancestor_at_finalized_slot != store.finalized_checkpoint.root:
                 store.justified_checkpoint = state.current_justified_checkpoint
 ```
-
diff --git a/specs/merge/validator.md b/specs/merge/validator.md
index 5b26a21dd..dccc5727b 100644
--- a/specs/merge/validator.md
+++ b/specs/merge/validator.md
@@ -48,7 +48,7 @@ Let `get_pow_chain_head() -> PowBlock` be the function that returns the head of
 
 ###### `produce_execution_payload`
 
-Let `produce_execution_payload(parent_hash: Bytes32) -> ExecutionPayload` be the function that produces new instance of execution payload.
+Let `produce_execution_payload(parent_hash: Hash32, timestamp: uint64) -> ExecutionPayload` be the function that produces new instance of execution payload.
 The body of this function is implementation dependent.
 
 * Set `block.body.execution_payload = get_execution_payload(state)` where:
@@ -62,9 +62,11 @@ def get_execution_payload(state: BeaconState) -> ExecutionPayload:
             return ExecutionPayload()
         else:
             # Signify merge via producing on top of the last PoW block
-            return produce_execution_payload(pow_block.block_hash)
+            timestamp = compute_time_at_slot(state, state.slot)
+            return produce_execution_payload(pow_block.block_hash, timestamp)
 
     # Post-merge, normal payload
     execution_parent_hash = state.latest_execution_payload_header.block_hash
-    return produce_execution_payload(execution_parent_hash)
+    timestamp = compute_time_at_slot(state, state.slot)
+    return produce_execution_payload(execution_parent_hash, timestamp)
 ```
diff --git a/specs/phase0/beacon-chain.md b/specs/phase0/beacon-chain.md
index cbd085bd3..3176d543c 100644
--- a/specs/phase0/beacon-chain.md
+++ b/specs/phase0/beacon-chain.md
@@ -157,6 +157,7 @@ We define the following Python custom types for type hinting and readability:
 | `ValidatorIndex` | `uint64` | a validator registry index |
 | `Gwei` | `uint64` | an amount in Gwei |
 | `Root` | `Bytes32` | a Merkle root |
+| `Hash32` | `Bytes32` | a 256-bit hash |
 | `Version` | `Bytes4` | a fork version number |
 | `DomainType` | `Bytes4` | a domain type |
 | `ForkDigest` | `Bytes4` | a digest of the current fork data |
@@ -164,6 +165,7 @@ We define the following Python custom types for type hinting and readability:
 | `BLSPubkey` | `Bytes48` | a BLS12-381 public key |
 | `BLSSignature` | `Bytes96` | a BLS12-381 signature |
 
+
 ## Constants
 
 The following values are (non-configurable) constants used throughout the specification.
@@ -374,7 +376,7 @@ class PendingAttestation(Container):
 class Eth1Data(Container):
     deposit_root: Root
     deposit_count: uint64
-    block_hash: Bytes32
+    block_hash: Hash32
 ```
 
 #### `HistoricalBatch`