w BAsO4 was previously synthesized by solid-state reactions at 800 degrees C and was characterized by X-ray powder diffraction. Now, we succeeded in preparing BAsO4 from 1131303 and As2O5 using hydrothermal synthesis by heating at 160 degrees C for 3 days (a single-phase product) and using microwave-assisted synthesis, which takes only 5 min to transform a solid mixture of As2O5 and (NH4)(2)B4O7.4H(2)O into the crystalline titled compound (a single-phase product). The crystallinity of the products is higher than that of the solid-state synthesized product given in the literature. Its X-ray powder diffraction patterns, and both Raman and IR spectra were in good agreement with the literature.