Chromium getters composed of strontium nickel oxide (Sr9Ni7O21) offer a cost-effective pathway for the mitigation of cathode poisoning in solid oxide fuel cells by capturing gaseous chromium species. The getter material, however, remains prone to chemical and structural changes in humid environments. Experimental observations indicate that Sr is segregated by absorbing H2O molecules and the resulting Sr-deficient phase is transformed into SrNiO3. Investigations reveal that the Sr-segregation is attributed not only to the hygroscopic nature of Sr but also to the compressive stress and 1D arrangement of Sr-ions in the structure. The formation of Sr(OH)(2)center dot 8H(2)O by moisture absorption accompanies volume expansion, resulting in crack formation. To improve the resistance to moisture attack, the surface is modified with SrCO3 layer by CO2-treatment. Experimental observations confirm that the SrCO3 passivation layer effectively restrains the moisture absorption and accompanied structural changes. The Cr-gettering capability of the SrCO3 layer on strontium nickel oxide is experimentally and thermodynamically verified. (c) The Author(s) 2019. Published by ECS.