A Rh/H-ZSM-5 catalyst has been found to catalyse the partial oxidation of methane at atmopheric pressure, and regular oscillations in both reactants and products have been observed. Temperature-programmed techniques, such as TPD, TPO and TPR, were performed to look into the reaction mechanism. The oscillatory behavior may be attributed to the synergism of the formate species and the oxide with certain interaction with the support. (c) 2005 Elsevier B.V. All rights reserved.