diff --git a/ethcore/res/tendermint.json b/ethcore/res/tendermint.json
index 38e5334a3..778757107 100644
--- a/ethcore/res/tendermint.json
+++ b/ethcore/res/tendermint.json
@@ -19,8 +19,12 @@
 	},
 	"genesis": {
 		"seal": {
-			"generic": {
-				"rlp": "f88980b8410000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000f843b8410000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
+			"tendermint": {
+				"round": "0x0",
+				"proposal": "0x0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
+				"precommits": [
+					"0x0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
+				]
 			}
 		},
 		"difficulty": "0x20000",
diff --git a/ethcore/src/spec/seal.rs b/ethcore/src/spec/seal.rs
index d5257ab79..967ffc22b 100644
--- a/ethcore/src/spec/seal.rs
+++ b/ethcore/src/spec/seal.rs
@@ -44,6 +44,16 @@ pub struct AuthorityRound {
 	pub signature: H520,
 }
 
+/// Tendermint seal.
+pub struct Tendermint {
+	/// Seal round.
+	pub round: usize,
+	/// Proposal seal signature.
+	pub proposal: H520,
+	/// Precommit seal signatures.
+	pub precommits: Vec<H520>,
+}
+
 impl Into<Generic> for AuthorityRound {
 	fn into(self) -> Generic {
 		let mut s = RlpStream::new_list(2);
@@ -52,6 +62,14 @@ impl Into<Generic> for AuthorityRound {
 	}
 }
 
+impl Into<Generic> for Tendermint {
+	fn into(self) -> Generic {
+		let mut s = RlpStream::new_list(3);
+		s.append(&self.round).append(&self.proposal).append(&self.precommits);
+		Generic(s.out())
+	}
+}
+
 pub struct Generic(pub Vec<u8>);
 
 /// Genesis seal type.
@@ -60,6 +78,8 @@ pub enum Seal {
 	Ethereum(Ethereum),
 	/// AuthorityRound seal.
 	AuthorityRound(AuthorityRound),
+	/// Tendermint seal.
+	Tendermint(Tendermint),
 	/// Generic RLP seal.
 	Generic(Generic),
 }
@@ -75,6 +95,11 @@ impl From<ethjson::spec::Seal> for Seal {
 				step: ar.step.into(),
 				signature: ar.signature.into()
 			}),
+			ethjson::spec::Seal::Tendermint(tender) => Seal::Tendermint(Tendermint {
+				round: tender.round.into(),
+				proposal: tender.proposal.into(),
+				precommits: tender.precommits.into_iter().map(Into::into).collect()
+			}),
 			ethjson::spec::Seal::Generic(g) => Seal::Generic(Generic(g.into())),
 		}
 	}
@@ -86,6 +111,7 @@ impl Into<Generic> for Seal {
 			Seal::Generic(generic) => generic,
 			Seal::Ethereum(eth) => eth.into(),
 			Seal::AuthorityRound(ar) => ar.into(),
+			Seal::Tendermint(tender) => tender.into(),
 		}
 	}
 }
diff --git a/json/src/spec/mod.rs b/json/src/spec/mod.rs
index f27b13b92..d923be069 100644
--- a/json/src/spec/mod.rs
+++ b/json/src/spec/mod.rs
@@ -34,7 +34,7 @@ pub use self::builtin::{Builtin, Pricing, Linear};
 pub use self::genesis::Genesis;
 pub use self::params::Params;
 pub use self::spec::Spec;
-pub use self::seal::{Seal, Ethereum, AuthorityRoundSeal};
+pub use self::seal::{Seal, Ethereum, AuthorityRoundSeal, TendermintSeal};
 pub use self::engine::Engine;
 pub use self::state::State;
 pub use self::ethash::{Ethash, EthashParams};
diff --git a/json/src/spec/seal.rs b/json/src/spec/seal.rs
index d586ed501..1cf1e86e6 100644
--- a/json/src/spec/seal.rs
+++ b/json/src/spec/seal.rs
@@ -39,6 +39,17 @@ pub struct AuthorityRoundSeal {
 	pub signature: H520,
 }
 
+/// Tendermint seal.
+#[derive(Debug, PartialEq, Deserialize)]
+pub struct TendermintSeal {
+	/// Seal round.
+	pub round: Uint,
+	/// Proposal seal signature.
+	pub proposal: H520,
+	/// Proposal seal signature.
+	pub precommits: Vec<H520>,
+}
+
 /// Seal variants.
 #[derive(Debug, PartialEq, Deserialize)]
 pub enum Seal {
@@ -48,6 +59,9 @@ pub enum Seal {
 	/// AuthorityRound seal.
 	#[serde(rename="authority_round")]
 	AuthorityRound(AuthorityRoundSeal),
+	/// Tendermint seal.
+	#[serde(rename="tendermint")]
+	Tendermint(TendermintSeal),
 	/// Generic seal.
 	#[serde(rename="generic")]
 	Generic(Bytes),
@@ -72,6 +86,14 @@ mod tests {
 				"step": "0x0",
 				"signature": "0x0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
 			}
+		},{
+			"tendermint": {
+				"round": "0x0",
+				"proposal": "0x0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
+				"precommits": [
+					"0x0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
+				]
+			}
 		}]"#;
 		let _deserialized: Vec<Seal> = serde_json::from_str(s).unwrap();
 		// TODO: validate all fields