Polysulfone gas separation hollow fiber membranes were manufactured using a dry/wet spinning process with forced convection in the dry gap. Hollow fibers were produced using two different bore coagulants: one pure water and one with reduced water activity. An optimized multi-component dope was used which proved to be a shear-thinning power-law fluid. For each bore system, membranes were spun at low and high dope extrusion rates (DERs) corresponding to shear rates of around 4000 s(-1) and 10 000 s(-1), respectively, at the outer spinneret wall. Plane polarized infrared spectroscopy was used to probe the membrane active layer. Pressure-normalized fluxes and selectivities were evaluated using purl carbon dioxide and methane. For the spinning conditions used here, the combination of reduced water activity in the bore and high DER produced highly selective membranes. Some selectivities reached about three times the recognized intrinsic value for the polymer.