diff --git a/contrib/launchtools/config.go b/contrib/launchtools/config.go
index e2d8847..c8c7063 100644
--- a/contrib/launchtools/config.go
+++ b/contrib/launchtools/config.go
@@ -89,6 +89,10 @@ type L2Config struct {
 	Denom   string `json:"denom,omitempty"`
 	Moniker string `json:"moniker,omitempty"`
 
+	// block parameters
+	BlockMaxBytes int64 `json:"block_max_bytes,omitempty"`
+	BlockMaxGas   int64 `json:"block_max_gas,omitempty"`
+
 	// BridgeID will be generated after the launch.
 	BridgeID uint64 `json:"bridge_id,omitempty"`
 }
@@ -106,6 +110,14 @@ func (l2config *L2Config) Finalize() error {
 		l2config.Moniker = "operator"
 	}
 
+	if l2config.BlockMaxBytes == 0 {
+		l2config.BlockMaxBytes = 5242880 // 5MB
+	}
+
+	if l2config.BlockMaxGas == 0 {
+		l2config.BlockMaxGas = 100_000_000 // 100M
+	}
+
 	return nil
 }
 
diff --git a/contrib/launchtools/steps/genesis.go b/contrib/launchtools/steps/genesis.go
index 2008538..ab54736 100644
--- a/contrib/launchtools/steps/genesis.go
+++ b/contrib/launchtools/steps/genesis.go
@@ -8,6 +8,8 @@ import (
 	"cosmossdk.io/log"
 	conmetconfig "github.com/cometbft/cometbft/config"
 	cometos "github.com/cometbft/cometbft/libs/os"
+	cmttypes "github.com/cometbft/cometbft/types"
+
 	"github.com/cosmos/cosmos-sdk/codec"
 	cryptotypes "github.com/cosmos/cosmos-sdk/crypto/types"
 	sdk "github.com/cosmos/cosmos-sdk/types"
@@ -220,6 +222,12 @@ func initializeGenesis(
 	appGenesis := &genutiltypes.AppGenesis{}
 	appGenesis.Consensus = &genutiltypes.ConsensusGenesis{
 		Validators: nil,
+		Params: &cmttypes.ConsensusParams{
+			Block: cmttypes.BlockParams{
+				MaxBytes: config.L2Config.BlockMaxBytes,
+				MaxGas:   config.L2Config.BlockMaxGas,
+			},
+		},
 	}
 	appGenesis.AppName = version.AppName
 	appGenesis.AppVersion = version.Version