This paper considers the application of inorganic membranes in conjunction with catalysis and discusses attempts which have been made to affect changes in the yields and product distributions in a number of catalytic reactions with a number of different conformations of catalyst and membrane. Various possible reactor conformations are first considered and then some results obtained for catalytically-active perm-selective membranes are presented to illustrate some of the problems encountered with such membranes. The use of non-perm-selective wall-and-tube reactors is then considered. Finally, the results of model calculations are presented which show that the most promising confirmation for the use of perm-selective membranes is one in which the membrane and catalyst are in separate units and external recirculation of reactants and products is carried out.