Proton exchange membrane fuel cells (PEMFC) are energy converters that can be used in nomad, automotive or stationary applications without emission of pollutants (gas or particles). The technology is already deployed in niches, but some drawbacks must still be overcome, such as the durability, which must be increased. It strongly depends on the PEMFC operating conditions (hydrogen purity, load cycle) and constitutive materials (bipolar plates, membrane). In particular, the corrosion of the carbon catalyst support is affected by various factors (potential, temperature, relative humidity, fuel starvation…), and critically decreases the PEMFC performances. It leads to the detachment and agglomeration of the catalyst nanoparticles, the decrease of the carbon hydrophobicity, affecting the water management, and the collapse of the carbon structure, both phenomena increasing the mass-transport losses. In this research, we modified the surface chemistry of the carbon support by modifying its hydrophobicity through controlled fluorination. In order to limit the corrosion induced by its surface oxygen content and the electrolyte, some of its dangling bonds were saturated with fluorine. Because a high specific surface area of the carbon support is important for a better dispersion of small platinum particle size and an adapted porosity is necessary to limit the mass transport losses, the study has been done on carbon aerogel (CA), which possess these two advantages [1]. The fluorination was carried out by decomposition of xenon fluoride [2] on either the CA or CA supporting platinum nanoparticles (Pt-CA). The platinum nanoparticles deposition (20 wt%) was achieved by "water in oil" method [3] on the AC and fluorinated CA (F-CA). The samples (CA, F-CA, Pt-CA, F/Pt-CA and Pt/F-CA) were texturally, morphologically and chemically characterized by XRD, TEM, nitrogen sorption, FTIR and TGA. The catalytic activity of the electrocatalysts for oxygen reduction was determined by cyclic voltammetry. Accelerated stress tests, conducted in a four-electrode cell, were performed to investigate the robustness of the fluorinated Pt electrocatalysts. The results are discussed and compared to those for a commercial 20 wt% Pt/XC72 E-Tek electrocatalyst. References : [1] M. Ouattara-Brigaudet et al., Int. J. Hydrogen Energy 37 (2012) 9742-9757 [2] M. Tramsek, B. Zemva, Acta Chim. Slov. 53 (2006) 105 [3] M. Simoes, S. Baranton, C. Coutanceau, Electrochim. Acta, 56 (2010) 580-591