In the present article, we have revisited the electronic band gap nature of ZnOxS1−x (0 ≤ x ≤ 1) with the recently developed modified Becke and Johnson exchange potential and the calculated band gaps are found consistent with the experimental results. We expect that the band gap bowing parameter obtained in the present work will be close to the experimental one. As the optical properties of ZnOxS1−x (0 ≤ x ≤ 1) are very important, therefore different optical parameters like dielectric functions, refractive index and reflectivity are also calculated. The results are illustrated in terms of band structures, band gap energy as a function of oxygen composition, total and partial density of states. © 2012 Wiley Periodicals, Inc.