Coconut wood polymer composites were prepared by impregnating the coconut wood with styrene and the combinations of styrene and methyl methacrylate under reduce pressure and subsequent polymerization by catalyst-heat treatment. Results of this study showed that 2% by wt. of methyl ethyl ketone peroxide, 70℃ curing temperature, 0.5 and 2 hours evacuating time, 1 and 4 hours soaking time for low and medium density coconut wood were suitable for preparation of coconut wood polymer composites. The physical and mechanical properties of coconut wood polystyrene composites were decreased by 63% and 53% in water absorption, 46% and 46% in volumetric swelling coefficient. They were increased by 117% and 50% in density, 100% and 19% in flexure stress, 72% and 27% in modulus of elasticity, 34% and 77% in compression when compared to low and medium density coconut wood, respectively. The physical and mechanical properties of coconut wood poly (ST-CO-MMA) composites were decreased by 39-50% and 19-29% in water absorption. 15-19% and 12-14% in volumetric swelling coefficient. They were increased by 68-79% and 34-48% in density, 21-68% and 8-16% in flexure stress, 3-30% and 18-25% in modulus of elasticity, 24-117% and 46-80% in compression when compared to low and medium density coconut wood, respectively. The morphology of the composites was examined using scanning electron microscopy.