In the present work, two nickel-iron-chromium-base superalloys, INCONEL718 and GH761, were heat-treated to obtain different microstructures in the alloys. The hydrogen permeability and diffusivity for the two alloys in various conditions were determined using a gaseous-hydrogen permeation technique to examine the influence of microstructures on hydrogen permeation behavior. Measurements were made over the temperature range of 210 °C to 430 °C. It was shown that the dependencies on temperature for hydrogen permeability and diffusivity for the two alloys obeyed the Arrhenius relationship over the test temperature range and that the precipitated strengthening phases hardly affected the hydrogen permeation and diffusion behavior for the INCONEL718 alloy, but the hydrogen permeability and diffusivity in the aged condition were all slightly lower than those in the solution-treated (ST) condition for the GH761 alloy.