Natural gas can be reformed to syngas (CH4 + H2O = CO + 3H(2)), at temperatures above 850 degrees C. Membrane catalytic reformers can provide high CH4 conversions at temperatures below 650 degrees C, by separating H-2 from the reactive mixture. Traditional Ni-based catalysts suffer from low activity at low temperatures and deactivate rapidly by coking, particularly at low steam/carbon ratios. In this study, an ultralow loading (0.15 wt %) Ru/gamma-Al2O3 catalyst was implemented in a lab-scale membrane reformer, using a supported 5 mu m Pd-Ag film membrane. Methane conversions above 90% were achieved at 650 degrees C, 8 bar, and H2O/CH4 = 2, 3 with contact times of ca. 10 s. The system generated up to 3.5 mol of ultrapure H(2 )per mol of CH4 fed, with a maximum power density of 0.9 kW/L. No significant deactivation was observed after 200 h time on stream, even when using low H2O:CH4 ratios. (C) 2018 American Institute of Chemical Engineers