An investigation was made into the effect of rf magnetron deposition parameters on the resulting properties of chromium oxide thin films. The films were sputtered in an argon/ oxygen plasma environment with the main deposition parameters being the argon and oxygen flow rate, chamber pressure, deposition-time and the deposition power (forward and back). Tire effect of the sputter deposition regime which is controlled by the sputtering hysteresis phenomenon i.e. the reactive and metallic regimes, are expected to have a significant effect on the properties of the sputtered films and will have to be taken into account. The films were deposited on a range of substrates such as silicon, glass micro-slides and stainless steel 304 and the composition of the mainly amorphous sputtered films was determined through XPS, EDX and XRD. Optical characterisation and determination of optical constants was undertaken by transmission/reflection spectrophotometry, ellipsometry and Raman and FTIR analysis. Two designs of a solar thermal absorber (multilayer interference and tandem absorber) were designed and fabricated based on the optical constants measured by the methods previously stated and their performance analysed. The surface energy was calculated through measurement of the contact angle with three different liquids and the corrosion resistance of the films measured by OCP, linear sweep and EIS analysis in 3.5wt% NaCI solution. The mechanical properties were measured by nanoindentation, from which the hardness and elastic modulus of the samples could be obtained. The electrical properties were measured using a four point probe to calculate the thin film resistivity and the Kelvin probe analysis was used to measure the work function of the samples.