Single-phase polycrystalline bismuth oxysulfate, Bi₂O₂SO₄, has been prepared via low-temperature reaction between Bi₂O₂CO₃ and (NH₄)₂SO₄. The compound is monoclinic (C2/m, a ​= ​14.1659(4) Å, b ​= ​4.2344(1) Å, c ​= ​8.2100(2) Å, β ​= ​106.7201(8)°, V ​= ​471.65(2) ų) and isostructural to isoelectronic Pb₂F₂SO₄ and to isolobal Ln₂O₂SO₄. Upon heating, it decomposes at ~550 ​°C into the Bi₂₈O₃₂(SO₄)₁₀ which is stable until ~775 ​°C. DFT calculations predict it to be a wide-gap semiconductor.