A theoretical investigation into the optimum pore structure of porous catalyst pellets, used for carrying out concurrent chemical reactions, is made. Results are reported in terms of optimum selectivity. It is observed that for concurrent reactions, optimum selectivity can be achieved in the Diffusion-Limited Region. The dependence of optimum selectivity upon the thermicity, β and α parameter & concerning energy of activation, is shown. For exothermic reactions at constant & optimum selectivity enhances with an increase in the thermicity whereas for endothermic reactions, converse is true. Also, at fixed value of β selectivity increases with an increase in the value of & for both exothermic and endothermic reactions; although the pattern in the two cases is different. The single variable search technique is used for carrying out optimization of the catalyst pore structure. Further study is undertaken to find the optimum selectivity and throughput for exothermic and endothermic consecutive catalytic reactions. The dependence of both the selectivity and throughput upon the thermicity and parameter concerning energy of activation is discussed.