Submicron size polyethylene particles were prepared by a thermally induced phase separation process in a split-and-recombine type micromixer. Process parameters such as polyethylene concentration, ratio of nonsolvent to solvent, initial temperature of the nonsolvent and total flow rate play important roles in controlling particle size. The results show that spherical polyethylene particles were obtained with an average diameter ranging from 0.22 mu m to 0.52 mu m. The continuous flow micromixer system prevented coagulation, therefore the size of the prepared polyethylene particles can be predicted using the continuous flow micromixer system. (C) 2011 Elsevier B.V. All rights reserved.