A process for simultaneously testing a plurality of catalysts using combinatorial chemistry has been developed. The process involves containing the plurality of catalysts in an array of parallel reactors with each reactor containing a bed of catalyst. Each bed of catalyst is then simultaneously contacted, at reaction conditions, with a reactant to form an effluent of each reactor. The reactant or an inert fluid is at a space velocity sufficient to fluidize the catalyst beds. Each of the effluents is analyzed.