Abstract Hydrogen storage alloy powders of rare-earth-based alloy-Ni systems (La-Ni, Mm-Ni-Co-Al, Mm-Ni-Co-Mn-Al; Mm = misch metal) were prepared by a reduction-diffusion process. The alloy powders were evaluated as a negative electrode in an Ni-metal hydride battery. The results are summarized as follows. (1) The alloy powder was obtained as fine particles of average particle diameter around 30 μm with smooth surface. (2) The alloy powder had uniform composition with a crystal structure of the CaCu 5 type. (3) The alloy powder exhibited good hydrogen absorption-desorption properties. The pressure plateau was very flat, not needing heat treatment. (4) The electrode properties of Mn-containing alloy powders were the same as those of alloys produced by a conventional induction melting and heat treatment process.