h i g h l i g h t s ◮ Catalytic palladium based membrane reactor is studied for ITER tritium waste management. ◮ Concentration polarization effect was highlighted by two-dimensional mass transfer model. ◮ Mass transfer resistance due to concentration polarization is reduced by the increase of fluid velocity. ◮ Concentration polarization phenomenon is enhanced by the decrease of non-permeable species content in the feed stream.