Yttria-stabilised zirconia electrolytes (YSZ and Pr-doped YSZ) and yttria-doped strontium cerate (SYC) were tested in a one chamber fuel cell fed with a mixture of methane and air at 1223 K. The obtained performances were 4 mW cm(-2), 3 mW cm(-2), 2.5 mW cm(-2), and 0.15 mW cm(-2) for SYC, 1.8 mol.% Pr-doped YSZ, 17 mol.% Pr-doped YSZ, and un-doped YSZ, respectively. These values are lower than those reported by Asano ct al., due to poisoning of the gold electrode. The solubility of hydrogen in the electrolytes was compared by means of tracer exchange using a H-2 + D2O mixture and subsequent SIMS analysis. Doping of Pr in the YSZ resulted in a higher intensity of the D ion, which indicated that hydrogen solubility was raised by the doping. The solubility of hydrogen in the electrolyte may affect the performance of one chamber fuel cells.