diff --git a/rust-evmjit/src/lib.rs b/rust-evmjit/src/lib.rs
index f1150ae40..3f3de7f4e 100644
--- a/rust-evmjit/src/lib.rs
+++ b/rust-evmjit/src/lib.rs
@@ -311,9 +311,6 @@ pub mod ffi {
 
 	#[no_mangle]
 	pub unsafe extern "C" fn env_sha3(begin: *const u8, size: u64, out_hash: *mut JitI256) {
-		// TODO: write tests
-		// it may be incorrect due to endianess
-		// if it is, don't use `from_raw_parts`
 		let out_hash = &mut *out_hash;
 		let input = slice::from_raw_parts(begin, size as usize);
 		let outlen = out_hash.words.len() * 8;
diff --git a/src/evm/env.rs b/src/evm/env.rs
index ac4292619..fcc5fe0bd 100644
--- a/src/evm/env.rs
+++ b/src/evm/env.rs
@@ -1,13 +1,32 @@
+//! Contract execution environment.
+
 use util::hash::*;
 use util::uint::*;
 use state::*;
 
+/// This structure represents contract execution environment.
+/// It should be initalized with `State` and contract address.
+/// 
+/// ```markdown
+/// extern crate ethcore_util as util;
+/// extern crate ethcore;
+/// use util::hash::*;
+/// use ethcore::state::*;
+/// use ethcore::evm::*;
+///
+/// fn main() {
+/// 	let address = Address::from_str("0f572e5295c57f15886f9b263e2f6d2d6c7b5ec6").unwrap();
+/// 	let mut data = RuntimeData::new();
+/// 	let mut env = Env::new(State::new_temp(), address);
+/// }	
+/// ```
 pub struct Env {
 	state: State,
 	address: Address
 }
 
 impl Env {
+	/// Creates new evm environment object with backing state.
 	pub fn new(state: State, address: Address) -> Env {
 		Env {
 			state: state,
@@ -15,17 +34,19 @@ impl Env {
 		}
 	}
 
-	pub fn sload(&self, index: &H256) -> H256 {
-		self.state.storage_at(&self.address, index)
+	/// Returns a value for given key.
+	pub fn sload(&self, key: &H256) -> H256 {
+		self.state.storage_at(&self.address, key)
 	}
 
-	pub fn sstore(&mut self, index: H256, value: H256) {
-		println!("index: {:?}, value: {:?}", index, value);
-		self.state.set_storage(&self.address, index, value)
+	/// Stores a value for given key.
+	pub fn sstore(&mut self, key: H256, value: H256) {
+		self.state.set_storage(&self.address, key, value)
 	}
 
-	pub fn balance(&self, _address: &Address) -> U256 {
-		unimplemented!();
+	/// Returns address balance.
+	pub fn balance(&self, address: &Address) -> U256 {
+		self.state.balance(address)
 	}
 
 	pub fn blockhash(&self, _number: &U256) -> H256 {
diff --git a/src/evm/evm.rs b/src/evm/evm.rs
index 41ce32b9e..0cf721b65 100644
--- a/src/evm/evm.rs
+++ b/src/evm/evm.rs
@@ -1,4 +1,4 @@
-//! EVM interface
+//! Evm interface.
 
 use evm::{RuntimeData, Env};
 
diff --git a/src/evm/runtime_data.rs b/src/evm/runtime_data.rs
index 7fba9362d..01adb34a3 100644
--- a/src/evm/runtime_data.rs
+++ b/src/evm/runtime_data.rs
@@ -1,3 +1,5 @@
+//! Immutable runtime data.
+
 use util::hash::*;
 use util::uint::*;
 
diff --git a/src/evm/vmfactory.rs b/src/evm/vmfactory.rs
index 404a95f46..306ec4e0f 100644
--- a/src/evm/vmfactory.rs
+++ b/src/evm/vmfactory.rs
@@ -1,4 +1,4 @@
-//! Vm factory.
+//! Evm factory.
 
 use evm::Evm;