Density functional theory is used to study Pt (1 1 1) surface oxidation via analysis of buckling, reconstruction, and variation of atomic charges on the top Pt layer at 0.50 and 0.5625 monolayers of adsorbed oxygen. Hydronium ions enhance oxidation and Pt buckling through proton transfer to the adsorbed O, whereas the chloride species plays an additional oxidant role enhancing Pt detachment. At the fuel cell operation temperature of 80 degrees C, ab initio molecular dynamics results after 4 ps suggest a small influence of the temperature on surface oxidation and moderate reconstruction effects. (C) 2010 Elsevier B.V. All rights reserved.