For proton exchange membrane fuel cells (PEMFCs), instability of Pt-based catalysts due to carbon support corrosion is a critical issue that limits their wide application. Alternative corrosion resistant supports, such as metal oxides, have been investigated in conductive carbon containing matrix and demonstrated improved stability. This study probes systematically the effects of Ti-O2 support particle size (5,18, and 30 nm) and Pt content (6, 12, and 37 wt%) on the oxygen reduction reaction (ORR) activity and stability of the Pt/TiO2 catalyst in the absence of corrosive carbon. The average Pt nanoparticle size increases with increased TiO2 support size and Pt content. For 12wt% Pt loading, with increasing support size the ECSA increases from 4.91 to 7.23 m(2)g(Pt)(-1), 6.5%-10.6% of the predicted electrochemical surface area, respectively. This result suggests that there is an increased support contribution with increased TiO2 support size to improve Pt accessibility. The mass and area specific ORR activities are the highest for the 12wt% Pt on 30 nm TiO2, 0.083 A mg(Pt)(-1) and 1134.56 mu A cm(Pt)(-2), respectively. Accelerated stress testing results in only a 5.9% loss in ECSA for the 12wt% Pt/TiO2 (30 nm) catalyst.