Gas-phase hydrogenation of o-xylene to cis- and trans-dimethylcyclohexane (DMCH) was studied in a differential ruicroreactor at atmospheric pressure and 430-520 K over a Pt/gamma-Al2O3 catalyst. Rapid reversible deactivation of the freshly reduced catalyst prompted reactivation before every kinetic measurement and extrapolation of the steady-state activity to initial activity. Reaction orders were close to zero for o-xylene and ranged from 1.5 (430 K) to 3.0 (520 K) for hydrogen. A rate maximum for the production of the saturated compounds was observed at about 460 K. The results were in line with previously reported results on xylene hydrogenation on Ni/gamma-Al-2-O-3 catalyst.