A thermogravimetric study of the oxygen gasi®cation of a commercial active carbon using Co, Ni and Cu as catalysts has been carried out. This follows a previous study of the in¯uence of the particle size, gas volumetric¯ow rate, initial sample weight temperature and oxygen partial pressure an non-catalytic gasi®cation. The results show that for T`500°C; P 02`1 atm; D p`0 .4 mm, Q v b 50 cm 3 min À1 and M o`7 5 mg the gasi®cation of the active carbon with oxygen is controlled by the chemical reaction. The presence of a catalyst increases in all cases the reaction rate, both temperature and catalyst concentration showing a very positive in¯uence. The activity of the different catalysts follows the order: Co b Cu b Ni. A kinetic study applied to both types of gasi®cation has allowed the activation energy and the reaction order with respect to oxygen and the catalyst to be determined. In all cases both the activation energy and the Arrhenius pre-exponential factor are lower in the catalytic gasi®cation. This brings about the existence of an isokinetic point for the catalytic and the non-catalytic processes, which were also determined.