Rapid straining electrode (RSE) test of nickel based alloys has been carried out under simulated primary water. Hydrogen absorption test and hump-SSRT in the pure hydrogen gas have also been carried out. The followings are clarified. The cathodic current observed in RSE test is strongly affected by dissolved hydrogen and the materials. Absorbed hydrogen in the metals depends on the materials in the pure hydrogen gas. These findings are related to PWSCC susceptibility of the materials considering the hydrogen in the metals should have important role for PWSCC.