This article presents a numerical study to investigate the effects of nonequilibrium chemistry, and in particular, wall catalysis on the separated flow region generated by an oblique shock wave impinging upon a flat plate boundary layer for a highly dissociated air flowfield. The results focus on the effects of the nonequilibrium chemistry upon the surface heat transfer and the separation zone size. Comparative results are given for chemically reacting (both noncatalytic and fully catalytic walls) and nonreacting flow cases. Furthermore, this comparison is extended over a wide range of freestream pressures (143-123,500 Pa) with a constant Reynolds number, Re = 1793. A direct comparison of all three cases, at low pressures, reveals a minimal change in the peak heat transfer for the noncatalytic wall case as compared to the calorically perfect gas case. In contrast, the fully catalytic wall exerted a tremendous increase in the surface heat transfer. However, as the freestream pressure is increased, significant recombination occurs, so the increase in the peak heat transfer for the noncatalytic wall is more pronounced. Whereas for the fully catalytic wall, at higher pressures, the increase in peak heat transfer is somewhat diminished due to the chemical recombination upstream of the reattachment point.