The design and development of highly efficient and stable non-noble metal electrocatalysts for hydrogen evolution reaction (HER) have attracted increasing attention. However, some key issues related to large overpotential, high cost and poor stability at high current density still remains challenging. In this work, we report a facile in-situ integration strategy of porous Ni2P nanosheet catalysts on 3D Ni foam framework (P-Ni2P/NF) for efficient and stable HER in alkaline medium. The two-step method can creates high density of ultra-thin porous Ni2P nanosheets firmly rooted into Ni foam substrate which can guarantee excellent electrical contacts, strong substrate adherence and large amount of active sites. Such a binder-free flexible HER cathode exhibits superior electrocatalytic performance with an overpotential of 134 mV at current density of 10 mA cm(-2). It also shows superior stability at higher current densities of 100 and 500 mA cm(-2) for at least 48 h and negligible performance degradation is observed. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.