Hydrogen evolution rate during the corrosion of stainless steel in supercritical water

•Interaction of supercritical water with stainless steel leads to large H2 release.•H2 evolution follows zero-order kinetics.•Surface-induced H2 evolution can minimize dissolved O2 levels.

The interaction of water with metal surfaces at high temperatures leads to the significant release of hydrogen gas. A systematic investigation of hydrogen evolution from fresh and oxidized stainless steel (SS316) surfaces is carried out in a tubular reactor, at supercritical water conditions. A linear relationship is found between the reactor surface area and the rate of hydrogen gas released. Results show that the evolution of hydrogen gas is a zero-order reaction, with the activation energy of 105.9 kJ mol−1 for the oxidized surface.