Herein we report the synthesis of highly cross-linked polymers based on divinylbenzene by heterogeneous polymerization in supercritical CO2 (scCO(2)). The polymers were isolated in the form of discrete microspheres (diameter = 1.5-5 mu m) in good yields (greater than or equal to 90%), in the absence of any stabilizers. In the presence of a CO2-soluble polymeric stabilizer, much smaller particles (diameter < 0.5 mu m) were formed in high yields (greater than or equal to 95%) by emulsion polymerization in scCO(2).