A new aromatic, tetrafunctional methacrylate monomer, 4,4′‐di(2‐hydroxy‐3‐methacryloyloxypropoxy)benzophenone, and its application to the synthesis of porous microspheres are presented. This new monomer was copolymerized with divinylbenzene in the presence of pore‐forming diluents. The properties of the obtained highly crosslinked microspheres were investigated as column packing for high‐performance liquid chromatography. Their porous structures in both dry and wet states were studied and compared with those of poly(divinylbenzene) and the less crosslinked copolymer of 2,3‐epoxypropyl methacrylate and divinylbenzene. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 7014–7026, 2006