Two phase transformations of TaVO5 were observed by DSC and/or dilatometry measurements in the studied temperature range. X-ray diffraction and neutron powder diffraction structure refinements indicated a phase transformation at -14 degrees C from a monoclinic symmetry with space group P2(1)/c to an orthorhombic symmetry with space group Pnma above this temperature. The rigid TaO6 octahedron in orthorhombic phase becomes nonregular at -14 degrees C, which results in the transition from Pnma to P2(1)/c. TaVO5 was found to be a negative thermal expansion material above room temperature. The calculated volumetric thermal expansion coefficients (TECs) are -8.92 x 10(-6) degrees C-1 in the range of 20-600 degrees C, and -2.19 x 10(-5) degrees C-1 above 600 degrees C, respectively. The negative thermal expansion behavior is accounted for by the tilt of the TaO6 and VO4 polyhedra, where the shrinkage of the VO4 tetrahedra result in the increase of Ta-O-V angles on heating, while the angle of Ta-O1-Ta maintains at 180 in the framework.