This work investigates the effects of hydrogen and stress on the electrochemical and passivation behaviour of 304 stainless steel in 0.5M sulfuric acid with 2 ppm sodium fluoride. Three major results are revealed: hydrogen and stress significantly increase the critical current density (i(crit)) and passive current density (i(pass)); hydrogen has a more obvious impact on i(crit) than that on i(pass); a high synergistic effect between hydrogen and stress on current densities is observed at the intermediate hydrogen charging current densities range. (c) 2018 Elsevier Ltd. All rights reserved.