High performance large surface area micro-porous silica membranes have been prepared using a robust method that combines reduced roughness of the membrane support surface with a straightforward coating procedure. The method allows for reproducible production of membranes with a flat plate or tubular geometry. Tubular membranes with a length suitable for commercial application (55 cm) show performance comparable, in terms of flux and permselectivity, to that of low surface area flat plate membranes and shorter tubes (10 cm). At 250 degrees C and pressure difference of 2 bar the hydrogen permeance of the 55 cm membranes is in the range (0.5-1) x 10(-6) mol m(-2) s(-1) Pa(-1), and the permselectivity of hydrogen with respect to methane is in the range 350-400. Permeation measurements below 400 degrees C over a period of more than 2100 h showed no significant changes in permeance or permselectivity. (C) 2009 Elsevier B.V. All rights reserved.