Abstract The crystal structure of β-VO(HPO 4) · 2H 2O has been determined from X-ray powder diffraction data. The cell is triclinic (space group P 1, Z = 4 ) with a = 5.659(2)Å, b = 7.578(4) Å, c = 12.623(5) Å, α = 89.66(2)°, β = 102.14(2)°, and γ = 92.23(2)°. Starting positional parameters were obtained by direct methods applied to 640 reflections which are derived from a modified Rietveld analysis working without structural model. The structure was refined using Rietveld profile refinement principles. The final reliability factors were R I = 0.039, R p = 0.076, and P wp = 0.092. The structure is built up of chains of corner-shared VO 4(H 2O) 2 octahedra and (HPO 4) tetrahedra alternated along the c crystallographic axis. These chains are interconnected through HPO 4 groups forming layers stacked in the  direction. In contrast to α-VO(HPO 4) · 2H 2O, there are no isolated water molecules between the layers.