In particular, the n-Pt/ AB800 and n-Pt/AB250 catalysts, possessing both the high effective Pt surface area (S(e)Pt) and the uniform distribution of the SSC ionomer, were able to achieve high mass power values over a wide range of RH (53e100%): 12.6e15.1WmgPt 1 (0.079e0.066 gPt kW 1) for n-Pt/AB800 and 13.2e15.4 W mgPt 1 (0.076e0.065 gPt kW 1) for n-Pt/AB250.