The reaction of methane (2%) with oxygen (2.8â 4.6%) in nitrogen at atmospheric pressure over Pd/Al2O3, Pdâ Pt/Al2O3 and Pd/Al2O3â CeO2 at temperatures in the range 250â 600 °C has been studied using catalytic microcalorimeters (beads) with simultaneous analysis of gas mixtures by FTIR. With close-to-stoichiometric gas mixtures, these catalysts showed oscillatory behaviour at 350â 550 °C. Oscillations were associated with changes in catalytic activity due to oxidation or reduction of the catalyst. Corresponding changes in morphology were also implicated by the enhanced thermal emissivity of the more active partially oxidised catalyst. Oscillations were weakened over Pd/Al2O3â CeO2 but were considerably enhanced over Pdâ Pt/Al2O3. Using two beads of Pd/Al2O3, interactions between oscillating systems were investigated. Heat-transfer effects were appreciable at separations of less than 2 mm but gas-phase communication, via changes in reactant concentrations, were observed at higher separations. Oscillations were eliminated at very close separations.