Abstract Mn-doped zinc oxide (ZnMnO) is of increasing interest to the optoelectronic community for thin film sensors, transistors and solar cells applications. Considerable variability exists in the literature on the growth and doping of ZnMnO films, especially as a function of growth approach, temperature, and oxygen partial pressure. We fabricated ZnMnO thin films on silicon substrates by pulsed laser deposition (PLD). The deposition pressure and the substrate temperature were varied from 2.67 Pa to 26.67 Pa, and from room temperature to 600 °C, respectively. The targets were fabricated with a nominal composition of 1, 5, 10, 15 and 20 wt.% Mn. The influence of the Mn composition, deposition pressure and the substrate temperature on optical properties of the ZnO films was investigated using ultraviolet– visible (UV–Vis) spectrometry. The optical band-gap of the films was evaluated in terms of the Kubelka-Munk function. The results show that the oxygen gas pressure has slightly affected the optical band-gap of the deposited films. Furthermore, the substrate temperature play significant role in the optical properties of the deposited ZnMnO thin films.