Hydrogen solubility in CuPd thin films was determined using a new electrochemical setup. The CuxPd100-x alloy thin films were prepared by pulsed potential co-electrodeposition and have a face-centered cubic (FCC) structure over the entire composition range (20 <= x <= 100). A subsequent heat-treatment at 400 degrees C induced a FCC to body-centered cubic (BCC) phase transition without any significant surface segregation, as illustrated in the case of the Cu59Pd41 thin film. It was demonstrated that the electrochemical setup permits, thanks to a constant renewal of the electrolyte, to minimize the anodic charge associated with the oxidation of dissolved H-2, and thus preventing an overestimation of the hydrogen solubility in these compounds. From electrochemical potential-composition isotherms performed in 0.1 M NaOH, it was shown that the maximum hydrogen solubility, (H/M)(max), decreases with the Cu concentration in FCC PdCu thin films (from 67 at.% for pure Pd to 3.6 at.% for Cu88Pd22). A comparison of the electrochemical isotherms of FCC and BCC Cu59Pd41 thin films confirmed that the maximum hydrogen solubility is much lower (by a factor of 5) and is reached at a more negative potential (higher hydrogen pressure) for the BCC structure. (c) 2012 Elsevier Ltd. All rights reserved.