A safe and reductant-free method based on co-reduction of nickel and copper oxides via vacuum thermal treatment has been developed for the synthesis of Ni-Cu alloy nanofibers, which includes electrospinning of a nickel acetate/copper acetate/polyvinylpolypyrrolidone (NiAc/CuAc/PVP) precursor solution, followed by vacuum thermal reduction. On account of the synergistic effect between Cu and Ni, the Ni-Cu alloy nanofibers catalyst with an optimal composition exhibits good catalytic performance for the decomposition of hydrous hydrazine in NaOH solution.Graphical AbstractNi-Cu alloy nanofibers have been prepared by a vacuum thermal co-reduction method, and further used as catalysts for hydrous hydrazine decomposition. [GRAPHICS]