Thermal stability of Hz-reduced MoO3 was investigated in connection with its catalytic property for the conversion of 2-propanol. MoO3 reduced at 623 K for 12 h had a surface area of about 180 m(2) g(-1) and pores with the diameter of 0.6-3.0 nm. The surface area and the porous structure of Ha-reduced MoO3 were retained even after treatment at 773 K in a N-2 atmosphere, indicating its high thermal stability. The dehydration and the dehydrogenation activities of H-2-reduced MoO3 in the conversion of 2-propanol were enhanced by thermal treatment in a N-2 atmosphere. The highest: dehydration activity was obtained after treatment at. 723 K. An increase in the amount of acid sites by thermal treatment was confirmed by NH3-TPD study.