An organic–inorganic, hybrid, low-melting glass free of pollution elements such as Pb and F was prepared through nonaqueous acid-base reactions of Si—Cl + P—OH ⇉ Si—O—P + HCl⇈ and Sn—Cl + P—OH ⇉ Sn—O—P + HCl⇈ using phosphonic acid (H3PO3), dimethyldichlorosilane (Me2SiCl2), and tin(II)chloride (SnCl2) as starting materials. Transparent, colorless, and homogeneous phosphite glass was successfully obtained. The formation of P—O—Si linkage and the disappearance of P—OH were confirmed by 31P nuclear magnetic resonance spectra. With increasing Si content, the glass-transition temperature decreased, reflecting the decrease of the average linkage number per one cation.