Ni3Al intermetallic compound has been known as promising high-temperature structural materials because of its excellent high temperature strength and corrosion/oxidation resistance. Recently, we found that Ni3Al shows catalytic activity for methanol reforming in the temperature range of 513-633 K. These results indicate that Ni3Al is promising as a catalyst for hydrogen production. In the present study, we examined the catalytic activity and stability of single-phase Ni3Al (Ni -24 at% Al) powder for hydrogen production from methanol at higher temperature (633-793 K) by isochronal and isothermal tests. It was found that the alkali-leached Ni3Al powder exhibited much higher catalytic activity and selectivity for the methanol decomposition than Raney Ni catalyst above 633 K. The hydrogen production rate increased with increasing temperature, and reached a peak (about 800 cm-3(STP) min-1 g-cat-1) near 713 K. During the isothermal test, the selectivities for the production of H2 and CO increased with reaction time and then stabilized at high level which was above 94% at 673 K, 93% at 713 K, 79% at 793 K, respectively. On the other hand, the selectivity for the production of CH4 decreased with reaction time during the initial period and then stabilized at low level, i.e. the formation of methane was suppressed significantly with the progress of reaction. Based on the surface characterization by SEM, TEM, XRD, and EDX analysis, we consider that the high selectivity and stable activity are due to the formation of porous surface structure consisting of fine Ni particles, alumina and carbon during reaction.