The conventional soybean oil hydrogenation process (metal catalyst on solid support particles slurried in oil, H-2 bubbled through the oil) is compared with metal-decorated integral-asymmetric polyetherimide (PEI) membranes, as far as changes in temperature and pressure are concerned. Using metal-decorated polymeric membranes, H-2 is supplied to the catalytic sites by permeation from the membrane substructure. As opposed to the slurry process, metal-decorated membranes show only slightly increased trans fatty acid (TFA) formation when the temperature is raised (50-90 degrees C) to accelerate the process. This is likely due to the efficient and to some extent self-regulating H-2 supply directly to the catalytic sites on the membrane skin. The hydrogenation rate and TFA formation of the metal-decorated membrane process show a minor dependence on pressure. (C) 2010 American Institute of Chemical Engineers AIChE J, 57: 2450-2457, 2011