The effect of hydrogen permeation on the corrosion performance of Alloy 22 was investigated. 50µm thick Alloy 22 membranes were permeated with Hydrogen under a cathodic charging current density of 1mA/cm2 in a Devanathan-Stachurski cell at 60ºC in pH 12.5, 0.1M NaOH solution. Anodic polarization scans of permeated and unpermeated samples were performed, under conditions with and without the addition of 0.1M sodium chloride in order to investigate the effect of a detrimental synergistic effect of hydrogen and chloride on the critical pitting potential (CPP) as reported in type 304 and 310 stainless steels. The thickness of the passive film before during and after hydrogen permeation was estimated using a parallel plate capacitor method. The diffusivity of hydrogen in Alloy 22 was estimated in the method outlined by ASTM standard G148-97. Alloy-22 was found to be particularly robust under hydrogen permeation. Passive film thickness was found to be independent of hydrogen concentration and no synergistic effect of chloride and hydrogen on CCP was found. The effective diffusivity of hydrogen in Alloy 22 was calculated to be 5x10-11cm2/s.