SO42-ZrO2 catalysts promoted with cations of transition metals (Fe, Cu, Ni, W, Pt, Co, Zn, Cd, Cr) were studied. Their influence on the catalytic activity for the isomerization of it-butane was analyzed in the presence of electron donor (H-2) and electron acceptor (O-2, CO2) gases. A new reaction scheme accounts for the one electron properties of the sulfate-zirconia catalyst. Transition metal cations are postulated to enhance activity through d-orbital interaction. Cations with a complete d level inhibit activity, but the presence of electron acceptor molecules (O-2 and CO2) in the reacting medium attenuated this deleterious effect.