The catalytic oxidation in air of o-xylene in low concentration (1700 ppm) was investigated over Pt/HBEA catalysts (framework Si/Al ratio equal to 15 and 50). Whatever the catalyst, o-xylene oxidation is accompanied by the retention of heavy compounds ("coke") within the pores. The higher the reaction temperature, the faster the xylene oxidation and the lower the coke formation. For a given zeolite support, the oxidation rate of o-xylene increases with platinum content. On the other hand, the higher the Si/Al ratio of the zeolite, the faster the o-xylene oxidation. Furthermore, the catalysts performances were enhanced by pre-reduction of platinum under hydrogen flow showing that Pt-0 species were very active for xylene oxidation. (C) 2003 Elsevier B.V. All rights reserved.