Thermal oxidative degradation of polystyrene doped with maleimidophenylmethacrylate derivatives which are succinimidophenylmethacrylates with substitutes of various molecular architectures in the imide cycle has been studied by dynamic thermogravimetry in air. The doping monomers (0.5-7 mol.%) have been built into polystyrene macromolecular chains by means of the copolymerization reaction. Succinimidophenylmethacrylates containing spatially non-hindered double bonds or bulky substitutes in the amide cycle show both inhibiting and retarding effects. The m- or p-substitutes have practically identical effect on the polystyrene resistance. The increase of the dopant content up to 5 mol.% results in a regular increase of the thermal stability of polystyrene.