This paper is about the kinetics of hydrolysis of biomass (Ailanthus altissima) using an aqueous alkaline-glycerol solution. The study was performed at four temperature levels (438, 458, 478 and 498 K) and for different times (1, 2, 3, 4, 5, 6, 7 and 8 hours). The solution concentration was constant (75 g glycerol, 25.0 g water, 10% NaOH and 10.0 g wood chips). After conversion has been determined, the fractional weight loss (-1/W-0 dW/dt) was found to be a function of the amount of wood residue (f(W)) and the reaction rate constant (k). The order of reaction (n) and activation energy (E-a) were calculated. The results were, respectively, 1.32 x 10(-2) s(-1), 1.16, and 19.5 kJ mol(-1) (C) 1999 Elsevier Science Ltd. All rights reserved.