We prepare Nation/Pt-C (where Pt-C is the carbon powder deposited on its surface with Pt particles) gas diffusion electrodes (GDEs) by ultrasonic spraying Pt-C/Nation ink solutions on the surfaces of carbon papers. The dispersion solvents of the catalyst ink solutions are alcohol/water mixture solutions containing 20-100 wt.% of alcohol, which possess δ = 23.4-11.3 and e = 78.4-19.9 (where δ and ε are the solvent solubility parameter and dielectric constant, respectively). We demonstrate that the morphology of Nation in the solutions and in the Pt-C/Nation GDEs strongly depends on the δ and ε of the dispersion solvents of catalyst ink solutions. The larger solvent δ and ε of the catalyst ink solutions result in the formation of larger and higher negatively charged Nation aggregated particles in the solutions, which leads to larger steric hindrance for depositing Nation ionomer on the surface of Pt-C particles when spraying the ink solutions on the surfaces of carbon papers. Thus a thinner Nation film is in contact on the Pt-C particle surfaces, which increases the Pt electrochemical catalytic surface area, leading to a higher fuel cell performance. The fuel cell performance exhibits strongly depending on the ε and δ values of the catalyst ink dispersion solvents for GDE fabrication.