The effects of thermodynamic parameters associated with low pressure H-2-steam on the oxidation behavior of Nickel have been investigated to simulate PWR primary water conditions. An Y2O3-ZrO2 solid state reference electrode operated between 372 and 480 degrees C, and exposed to variable hydrogen partial pressures, was used to obtain in-situ potential measurements to identify the Ni/NiO transition. Microstructural analyses on Alloy 600 coupons exposed to H-2-steam under different oxidizing conditions showed a marked dependence of the intergranular oxidation processes, as expected for a PWR environment. Overall, the H-2-steam simulated an environment that can be considered to be representative of PWR primary water. (C) The Author(s) 2019. Published by ECS.