NiO/Nb2O5/C (8:1), (4:1), (2:1), NiO/C, and Ni/C catalysts for hydrazine electrooxidation were synthesized by an evaporation drying method followed by thermal annealing. Prepared catalysts were characterized by X-ray diffraction (XRD), high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM), energy dispersive X-ray spectrometry (EDS), and X-ray absorption fine structure (XAFS). Catalytic activity, durability, and selectivity in the reaction of hydrazine electrooxidation were evaluated in alkalinemedia. The highest catalytic activity in mentioned above reactionwas found forNi/C, followed by:NiO/Nb2O5/C (8:1), NiO/Nb2O5/C (4:1). NiO/Nb2O5/C (2:1) whiles NiO/C has almost no activity for hydrazine oxidation. NiO/Nb2O5/C (8:1) and (4:1) had a highest stability during electrooxidation of hydrazine at 60 degrees C. It was explained by oxygen defect of NiO in NiO/Nb2O5/C from XAFS analysis. The selectivity hydrazine electrooxidation as measured by ammonia production resulted in observation that metallic Ni surface facilitates N-N bond breaking of hydrazine, which was confirmed by density functional theory (DFT) calculations. (C) The Author(s) 2017. Published by ECS. All rights reserved.