The thermokinetic behavior of blocked polyurethane (PU)-unsaturated polyester (UP)-based composites during the pultrusion of glass-fiber-reinforced composites was investigated utilizing a mathematical model that accounted for the heat transfer and heat generation during curing. The equations of continuity and energy balance, coupled with a kinetic expression for the curing system, were solved using a finite difference method to calculate the temperature profiles and conversion profiles in the thickness direction in a rectangular pultrusion die. A kinetic model, dP/dt = A exp(-E/RT)P-m(1 - P)(n), was proposed to describe the curing behavior of a blocked PU-UP resin. Kinetic parameters for the model were obtained from dynamic differential scanning calorimetry scans using a multiple regression technique, which was able to predict the effects of processing parameters on the pultrusion. The effects of processing parameters including pulling speed, die wall temperature, and die thickness on the performance of the pultrusion also were evaluated. (C) 2003 Wiley Periodicals, Inc.