BPO(4) was previously synthesized by the solid state reactions of (NH(4))(2)HPO(4) and B(2)O(3) at 1000 degreesC and was characterized by X-ray powder diffraction and IR methods. We have now succeeded in preparing BPO(4) from H(3)BO(3) and P(2)O(5) using hydrothermal synthesis by heating at 160 degreesC for 2 days and obtained a single phase product. We observed that a microwave-assisted synthesis takes only 3 to 5 minutes to transform a solid mixture of (NH(4))(2)B(4)O(7). 4H(2)O, and solid H(3)PO(4) Or B(2)O(3) + P(2)O(5) into the crystalline title compound. Its X-ray powder diffraction data and IR spectra were in good agreement with the literature values.