The phase diagram of the BaO-CuO-V(2)O(5) system in air was studied by X-ray powder diffraction. The existence of the nonconducting orthorhombic compounds BaCuV(2)O(7) (a = 15.051 angstrom, b = 15.450 angstrom, c = 15.175 angstrom, Z = 24) and SrCuV(2)O(7) (a = 14.496 angstrom, b = 15.404 angstrom, c = 15.025 angstrom, Z = 24) and a tetragonal compound BaCu(2)V(2)O(8) (a = 12.744 angstrom, c = 8.148 angstrom, Z = 8, T(m) = 760 degrees C) has been confirmed, and their diffraction patterns are presented.