The development of high-performance Ni catalysts including the formation and stabilization of active Ni nanoparticles with high surface areas by increasing their metal dispersion at the high metal loading have been major issues in the design of a compact reformer for hydrogen production. Herein, we first report a facile method based on the sequential melt infiltration process for creating highly dispersed Ni nanoparticles (~7.5 nm) incorporated into alumina support (Ni/Al2O3) with high Ni load (45 wt%). They showed much higher hydrogen productivity and reaction rate than that of the incipient wet-impregnated Ni catalyst and commercial Ni catalyst as well as good thermal stability in steam-methane reforming under harsh conditions.