The vacuum ultraviolet (VUV) to near infrared emissions(112⩽λ⩽880 nm)from molecular gases (H2andO2) and molecular gas–noble gas mixtures (H2–ArandO2–Ar) have been investigated with two separate spectrophotometric instruments. We report the influence of plasma parameters such as gas composition, pressure, and microwave power upon the plasma emission. In the case of mixtures with noble gases, we selected a range of plasma parameters so as to obtain very intense VUV emissions, which can be useful for the photochemical treatment of polymer surfaces. Some kinetics mechanisms involved are discussed.