Fill a large saucepan with 1 inch of water. Set a steamer basket in the saucepan and bring the water to a boil. Add the Brussels sprouts to the steamer basket, cover and cook over moderately high heat until the brussels sprouts are bright green and tender, about 6 minutes.
Transfer the Brussels sprouts to a bowl with the butter and chives. Toss until the butter is melted and coats the Brussels sprouts. Season with salt and pepper and serve.