The new aromatic tetrafunctional methacrylate monomer, 1,4-di(2-hydroxy-3-methacryloyloxypropoxy)phenol, and its application for the synthesis of porous microspheres have been presented. It was copolymerized with trimethylolpropane trimethacrylate in the presence of pore-forming diluents mixture (chlorobenzene and 1-decanol). The results indicate that composition of diluents mixture influence porous structure of copolymers. The porous structure of the copolymer obtained in the presence of 50% chlorobenzene was studied in detail. The results show that pore volume and the most probable pore size diameters determined for the copolymer in the dry and in the wetted states are different. (C) 2007 Wiley Periodicals, Inc.