This work represents the results of the theoretical study of the distribution of concentration and temperature in porous catalyst, carried out over spherical iron oxide/chromia catalyst pellets for the water-gas shift reaction (WGSR). The kinetic information has been taken from an earlier study (G.C. Chinchen et al., Appl. Catal., 12 (1984) 97) for the above reaction. The mass and heat transfer distribution coupled with chemical reaction, outside and within the catalyst particles for water-gas shift reaction was estimated in this present study. A computer program was written to calculate both concentration profile and temperature profile for the water-gas shift reaction.