Measurements have been made of the kinetics of oxidation over palladium of the C
1
to C
4
alkanes, cyclopropane and cyclohexane in the temperature range 588-873 K by means of a microcalorimetric bead technique. With an initially reduced and degassed catalyst, reaction rates for the alkanes increase from C
1
to C
4
, while butane, cyclopropane and cyclohexane are of comparable reactivity. The rates of oxidation of the alkanes are significantly increased when the catalyst is preheated in oxygen, and cyclopropane oxidation is markedly enhanced by this procedure. Reactions are inhibited by gas-phase diffusion effects, particularly at higher temperatures; there is thus apparent inhibition by oxygen. All the reactions are preceded by the surface oxidation of the catalyst, this latter process having an activation energy of 176 ± 18 kJ mol
-1
. Reaction appears to involve the interaction of hydrocarbon from the gas phase with palladium oxide, followed by the rapid desorption of carbon dioxide and the slower desorption of water. Large concentrations of water vapour cause a loss of catalytic activity, probably due to the formation of palladium hydroxide. When the bead system is used for the detection of low concentrations of hydrocarbons, the optimum operating temperature lies between 793 and 723 K, decreasing as the hydrocarbons become more reactive. The most significant single factor governing response is the heat of combustion, so that this method is most sensitive for the determination of high molecular mass hydrocarbons.