Abstract: The structural aspects of sulfur incorporation in borosilicate glasses were studied in the paper. Understanding of the structural aspects may provide theoretical basis for increasing the sulfur solubility in the glass. Sulfur XANES (X-ray absorption near-edge spectroscopy) spectra of several crystalline standards were collected. By comparing sulfur XANES spectra in the glass and those in crystalline standards, it can be concluded that the sulfur is present as SO^2-₄ and no reduced sulfur is observed in the borosilicate glass. The results also indicate that SO^2-₄ is surrounded by network modifying cations.