The tensile and impact properties of X70 pipeline steels exposed to wet H2S environments were investigated by corrosion and mechanical testing. The results suggest that the Charpy absorbed energy, tensile strength and reduction in area of X70 steel decreased after H2S corrosion. When hydrogen was released, Charpy absorbed energy and reduction in area exhibited a certain recovery. Fractography of the tensile and impact specimens exhibited mixed ductile-brittle rupture after corrosion and hydrogen release. Fractured areas with brittle features diminished after hydrogen release. Hydrogen was closely associated with mechanical property degradation and fracture features. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.