Seven carbon aerogels (CAs) with different pore size distributions were synthesized and used as a catalyst support in proton exchange membrane fuel cell (PEMFC) cathodes. The cathodes were tested in 50 cm 2 membrane electrode assemblies. The results demonstrate that the CA texture significantly influences performance by impacting gas diffusion and proton transport. Also, the Nafion ® loading must be adapted to the CA texture, since its easier penetration into large pores favors their obstruction and results in higher proton resistance and mass-transport voltage losses. Under fixed experimental conditions (notably Nafion ®/carbon ratio = 1), the best CA support displays high specific surface area and pore volume, a majority of mesopores with a pore size distribution peak around 25-30 nm and with some macropores. The work confirms that the carbon support structure must be controlled to reduce mass-transport voltage losses. Doing so would lead to reduce PEMFC overall cost per kW.