White pine wood was impregnated with a mixture of methyl methacrylate (MMA) and N‐methacryloyloxyphthalimide and by other three mixtures prepared by mixing MMA and N‐methacryloyloxytetrabromo‐phthalimide. Water uptake of treated wood was found to be 54 per cent after water‐soaking test of 168 h and maximum antiswell efficiency was found to be 48 per cent for treated wood samples with non‐brominated comonomer mixture.