NPR, a material consisting of a novolac resin blended with poly(2-methyl-l-pentene sulfone) (PMPS), is an attractive positive electron beam resist. However, it exhibited a number of problems during processing. For example after the development step, NPR patterns were surrounded by a halo due to resist thickness differences in the region next to the exposed areas. Also, a thin residual film appeared in the developed regions. A study of these problems showed that immiscibility between the two NPR components was responsible for many of the results. Also, Fourier Transform Infra Red Spectroscopy showed that a low molecular weight PMPS, [n] - 20 cm3/g, considerably improved compatibility and reduced the defects mentioned above. For this reason a study of PMPS molecular parameters by Gel Permeation Chromatography (GPC), light scattering and intrinsic viscosity was undertaken. This study related the molecular variables to synthetic conditions and a reproducible synthesis was established. A new NPR system was prepared with 9% low molecular weight sulfone polymer. This resist exhibits good film quality after development and displays a sensitivity of 8pC/cm2 with excellent (0.25μm) resolution.