Analysis of the literature on (x-methylstyrene (AMS) hydrogenation reveals very large variations in the reported reaction rates. The presence of traces of water and mass-transfer limitations make reproducible intrinsic kinetic determination difficult. Under anhydrous conditions, the intrinsic kinetic law was, nevertheless, determined under a wide range of operating conditions: 0.5-100 wt % AMS, 0.1-0.6 MPa, 273-320K, with an activation energy of 38.7 +/- 1.5 kJ(.)mol(-1).