Efficient and robust Earth-abundant catalysts for hydrogen evolution reaction (HER) is one of the key components for clean energy technologies aimed at reducing future carbon emissions. Here, an in-situ anion exchange approach to prepare hierarchical nano structures consisting of ultrathin Cu2-xSe nanosheet is reported. With the aid of the selenylation process and the hierarchical ultrathin nanostructure, the nanostructured Cu2-xSe/Cu foam electrode achieved considerably enhanced HER performance with a large geometric current density of -100 mA cm(-2) at a small overpotential of 313 mV and outstanding long-term operational stability. Significant improvement of electrocatalytic activity for Cu2-xSe catalyst could be attributed to the promoted mass diffusion/transfer properties, which results from its special structural feature. Meanwhile, the overpotential associated with the catalyst/substrate interface could be effectively eliminated due to the self-supported construction. We believe that this work will lead towards the further development of Cu-based chalcogenides for applications in electrocatalysis and energy conversion. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.