The stability of carbon-supported Pt electrocatalysts is long regarded as a critical issue. In this study, we demonstrate that by physically mixing a commercial Pt/C catalyst with 20 wt% of 2-dimensional tungsten oxide (WO3) nanoplates, the stability of the Pt/C-WO3 composite is greatly improved as both ECSA and catalytic activity are maintained approximately twice higher than the commercial Pt/C after a long-time accelerated degradation test. Interestingly, Pt nanoparticles are observed to migrate or re-nucleate on the surface of WO3 nanoplates from the carbon surface during degradation, which circumstantially triggers the 'hydrogen spillover' effect between Pt and WO3, and results in the CO stripping peaks being gradually shifted towards lower potentials. The outcome of this work provides crucial insight regarding the degradation behaviors of Pt nanoparticles in a heterogeneous catalyst system and can lead to the development and design of other stable Pt-based electrocatalysts. (C) 2015 Elsevier Ltd. All rights reserved.