A model Pt catalyst nanoarray on planar glassy carbon (GC) was synthesized using a diblock copolymer synthesis route and subjected to a potential cycle aging procedure. Preliminary experimental data show initial and degradation behavior similar to that of proton exchange membrane fuel cell gas diffusion electrodes. Commonalities include similar cyclic voltammetry and CO stripping voltammetry features, Pt active surface area temporal changes, and Pt particle size effect on CO oxidation peak potential. Furthermore, atomic force microscopy provides evidence for both Pt dissolution and Pt nanoparticle migration/coalescence as aging mechanisms. Experimental data obtained with Pt model catalysts also revealed that Pt dissolution may be the rate-determining step under certain operating conditions. Thus, the beneficial use of Pt/GC model electrocatalysts as surrogates for commercial gas diffusion electrodes is validated.