Porous polymer monoliths have been successfully prepared by photoinitiated polymerization of butyl methacrylate (BMA) and ethylene glycol dimethacrylate (EDMA) monomers in porogenic solvent of methanol. Mercury intrusion porosimetry and scanning electron microscope are used to characterize the porous properties; nevertheless, the pore size obtained from both techniques is not comparable. The porous structure of the porous polymers is controlled by the phase separation during the polymerization and crosslinking. By varying the composition of the starting solution such as initiator fraction, BMA/EDMA ratio, porogen fraction, and UV intensity, porous polymers with median pore size from about 140 nm to 3 mu m can be obtained, and the pore size distribution for majority of the porous polymers is also narrow. The results present a very positive prospect to microfluidic applications. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 120: 3190-3195, 2011