The use of water as a nucleophile for Michael additions is still a challenge in organic chemistry. In this report we describe the use of amino acids as catalysts for the Michael addition of water to ?,?-unsaturated ketones. All 20 proteinogenic amino acids were screened and L-lysine was identified as the best candidate. To obtain a better insight and to determine the minimum requirements of the catalyst, several structurally related compounds were tested. The reaction was characterized in terms of conditions and equilibrium.