Thin films of &agr;‐sulfur were prepared on quartz plates by a high‐vacuum thermal‐evaporation method. In an optical investigation of the thin films at room temperature, a direct allowed transition at 4.43 eV was observed. An indirect allowed transition was also observed with a band gap of 2.61 eV and assisting phonons of 0.11 eV. These observations were supported by reflectivity data obtained by an integrating sphere.