We prepared a series of Pd catalysts for total oxidation of methane on different supports: Al2O3, ZrO2-CeO2 and CeO2. We characterized the catalysts' structures by XRD and their surface chemistries by temperature programmed reduction (TPR) and oxidation (TPO); and measured their activities for methane oxidation in temperature programmed reaction experiments (TPRx). By fitting a kinetic model to the TPRx results, we extracted apparent activation barriers (E-app) and pre-exponents (A(app)) for methane oxidation over each of the catalysts. Activity correlates strongly with Aapp, which we interpret as a relative measure of the density of PdO-Pd* (* is an O-vacancy) site pairs. TPR results support this view: PdO in low activity (low A(app)) catalysts, such as Pd/CeO2, is relatively resistant to reduction, meaning that formation of the Pd* partner of the site pair is difficult and the number of site pairs that can form is low. (C) 2015 Elsevier B.V. All rights reserved.