Methacrylate monolithic columns (320 µm i.d.) for capillary liquid chromatography (CLC) have been prepared by radical polymerization of butyl methacrylate and ethylene dimethacrylate (EDMA) in the presence of a porogen solvent consisting of propan-1-ol, butane-1,4-diol and water. The contents of EDMA and of the porogen solvent were varied in the polymerizations. The column efficiency (height equivalent to theoretical plate, HETP) was determined for a set of test compounds as a function of the mobile phase flow rate. The composition of the polymerization mixture was optimized to achieve a minimum HETP.