A kinetic study has been made on the radiation induced polymerization of an acrylic acid-silica system. The effect of temperature and silica on the percentage conversion of monomer to polymer was studied. The rate of formation of polymer at the same temperature in the composite system was found to be faster when compared to bulk acrylic acid system at the same dose. This acceleration showed that the silica had a catalytic effect on the formation of polymer, The kinetic analysis of the conversion curves was made according to equations developed by Magat for nonsteady state polymerization laking place in precipitating media, k(p)/k(1) ratio determined for polymerization of acrylic acid in presence of silica was found to be much higher than for bulk acrylic acid polymerization. The augmentation in rate is mostly attributed to the orientation effect of silica surface and increased secondary electrons produced in the irradiation of a composite system. (C) 1998 Elsevier Science Ltd. All rights reserved.