Dilatometric examination was used to investigate the sintering of the higher-pressure water atomized Ni-20%Cr super fines. It was confirmed that sinterability of the super fines was superior to alloy powders atomized with the ordinary water pressures. Sintering in hydrogen atmosphere improved the sinterability of the Ni-20%Cr super fines, which was due to the fact that the main sintering mechanism of Ni-20%Cr super fines in hydrogen atmosphere was volume diffusion while grainboundary diffusion was the main mechanism in both argon and vacuum atmosphere.