Electrochemical performance of Ni2SnP was assessed in Li-ion and Na-ion battery systems. When cycled versus Li, Ni2SnP exhibited a reversible specific charge of 700 mAh.g(-1) (theoretical specific charge: 742 mAh.g(-1)). In the Na system, the specific observed charge was ca. 200 mAh.g(-1) (theoretical specific charge: 676 mAh.g(-1)). X-ray diffraction, Ni K-edge X-ray absorption spectroscopy, and P-31 and Li-7/Na-23 nuclear magnetic resonance spectroscopy were used to elucidate the electrochemical mechanisms in both systems. Versus Li, Ni2SnP undergoes a conversion reaction resulting in the extrusion of Ni and the alloying of Li-Sn and Li-P. On delithiation, the material partially recombines into a Sn- and Ni-deficient form. In the Na system, Ni2SnP reacts through the conversion of P into Na3P. These results indicate that the recombination of the pristine material (even partially) increases cycling stability. (C) 2017 Elsevier B.V. All rights reserved.