The hydroxymethylation of phenol in alkaline conditions is the first step in the synthesis of resols, which must be later cured for the production of final articles. A mathematical model for the hydroxymethylation of phenol is presented. It is based on the kinetic mechanism by Freeman and Lewis (J. Am. Chem. Soc. 1954, 76, 2080-2087) and includes a set of side reactions. Arrhenius expressions for the seven hydroxymethylation kinetic constants at pH 8-10 and temperatures 30-57 degrees C, and in the absence of methanol, were recalculated from the constants reported by Zavitsas et al. (J. Polym. Sci, Part A-I: Polym. Chem. 1968, 6, 2541-2559), in order to take into consideration the hydration/dehydration of formaldehyde and other side reactions. The model adequately predicts the measurements in the mentioned publications and in Higuchi et al. (J. Wood Sci. 1999, 45, 306-312). All of the kinetic parameters were directly or indirectly taken from the literature and were not readjusted to the measurements.