Styrene/ methyl methacrylate (St/MMA) copolymer particles were synthesized by suspension polymerization process in a certain composition to prepare (St/MMA) copolymer microcellular foams in different temperatures and pressures using supercritical CO2. Microcellular foams were successfully prepared in a high pressure CO2chamber. Study of the morphological properties of foams was the next step. For finding of optimized foaming condition; at first, foam samples were produced in a certain pressure and different temperatures to find optimized temperature of foaming. After that foaming process was repeated at different pressures but in optimized temperature to find optimized pressure of foaming. The cell microstructure of foams was studied by scanning electron microscopy. Produced foams have an average cell size ranging from 1um to 20um. Foams density was measured under 0.2 g/cm3.