Copolymerisation of N-phenyl maleimide (NPM) and γ-methacryloxypropyl trimethoxy-silane (MTS) in dioxan solution using benzoyl peroxide as an initiator is described. The rate of copolymerisation depended on the mole fraction of NPM in the initial feed and decreased with an increase in NPM content. Copolymers having a mole fraction of NPM varying from 0.29 to 0.55 exhibited similar thermal behaviour in terms of initial decom-position temperature or temperature of maximum rate of weight loss. However, char yield at 600°C depended on NPM content, showing a tendency to increase with the increase in NPM content. © 1993 John Wiley & Sons, Inc.