V 2 O 3 nanopowder with spherical particles was prepared by reducing pyrolysis of the precursor, (NH 4 ) 5 [(VO) 6 (CO 3 ) 4 (OH) 9 ].10H 2 O, in H 2 atmosphere. The thermolysis process of the precursor in a H 2 flow was investigated by thermogravimetric analysis and differential thermal analysis. The results indicate that pure V 2 O 3 forms at 620 o C and crystallizes at 730 o C. The effects of various reductive pyrolysis conditions on compositions of V 2 O 3 products were studied. Scanning electron micrographs show that the particles of the V 2 O 3 powder obtained at 650 o C for 1h are spherical about 30nm in size with more homogeneous distribution. Experiments show that nanopowder has larger adsorption capacity to gases and is more easily reoxidized by air at room temperature than micropowder. Differential scanning calorimetry experiment indicates that the temperature of phase transition of nano-V 2 O 3 powder is -119.5 o C on cooling or -99.2 o C on heating. The transition heats are -12.55Jg - 1 on cooling and 11.42Jg - 1 on heating, respectively.