Amino acids can be recovered from hog hair using sub-critical water hydrolysis. Since the reaction kinetics in sub-critical water is very complicated, a simplified kinetic model to describe the hydrolysis of hog hair is proposed: the reaction follows a cero order reaction for the first 45 min and a single consecutive reaction after this time. The differential equations resulting from model were fit to experimental data to obtain kinetic rate constants. A good agreement between the simplified model and the experimental data was obtained. (c) 2008 Elsevier B.V. All rights reserved.