Barrier height (Phi(BH)) values for Pd/hydrogen-terminated diamond (H-diamond) and Pd/oxygen-terminated diamond (O-diamond) have been investigated by X-ray photoelectron spectroscopy technique. H-diamond and O-diamond have been formed on the same diamond (100) layer grown by microwave plasma-enhanced chemical vapor deposition, on which Pd layers have been evaporated. The Phi(BH) values for Pd/H-diamond and Pd/O-diamond are determined to be -0.27 eV and 1.73 eV, respectively. It indicates that Pd is a suitable metal for ohmic and Schottky contacts on H-diamond and O-diamond, respectively. The experimental Phi(BH) values are in good agreement with the theoretical calculation results. (C) 2016 Elsevier B.V. All rights reserved.