Tunable optoelectronic properties of Molybdenum oxide (MoO3-x) make it a suitable applicant for its use as a catalyst and a hole transport layer. Oxygen vacancies play a vital role in deciding the properties of MoO3-x. In this article, the influence of deposition conditions like substrate temperature and gaseous environment on optoelectronic properties of MoO3-x films are investigated. Increase in substrate temperature have formed oxygen deficient MoO3-x films having lesser transmission (∼30%) and higher conductivity (15-200 Ω−1cm−1). Films prepared at the substrate temperature of 400 °C and rf-power 80 W are mostly crystalline and have led to the formation of MoO2 along with MoO3-x which results in highly conducting less transparent film suitable for catalysis application. Further, introduction of oxygen gas during deposition led to the formation of highly transparent (∼80%) and resistive (10−6 Ω−1cm−1) thin films suitable for hole transport layer application. An increase in oxygen concentration and decrease in oxygen vacancy is confirmed by energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy measurement respectively for films deposited in presence of oxygen gas. These studies imply that stoichiometry of molybdenum oxide can be controlled by varying the film preparation conditions and thus optoelectronic properties can be tuned accordingly.