This article reports the chemical modification of an atactic polypropylene performed in solution. To model the process, a Box-Wilson experimental design was used, taking in to consideration the concentrations of maleic anhydride and dycumile peroxide, as well as reaction time, as independent variables. The dynamic character of the process is proposed on the basis of model forecasts supported by experimental results. The proposed kinetic pathway agrees with the fact that short reaction times are not only sufficient but necessary for the greatest graft yields to be attained, while preventing degradative processes in the system. (c) 2006 Wiley Periodicals, Inc.