Membrane based separation technologies offer energy and cost efficient alternatives to conventional thermally driven separation processes.Application of microporous membranes in the water gas shift reaction at 250-300C to drive the equilibrium limited reaction in the forward direction can increase the overall efficiency of the hydrogen production process from the steam reforming of natural gas. The scope of this book is presenting experimental studies on membranes for high temperature gas separations, particularly hydrogen-carbon dioxide separations. To withstand high temperatures, inorganic microporous silica and silica-titania membranes were developed through novel techniques. High temperature resistant polymer based membranes were also studied.