© 2015 Elsevier B.V. All rights reserved. In this work the potential of thin manganese oxide layers deposited by physical vapor deposition at moderate vacuum pressure to significantly retard the corrosion of silicon photo-anodes during the oxidation of water is reported. Results show that manganese oxide layers up to 10 nm thick display sufficient transmission of solar frequency radiation and electrical conductivity to facilitate efficient oxidation of water by the underlying silicon while offering complete protection from oxidation of the silicon substrate for more than 14 h. Data from x-ray photoelectron spectroscopy confirms that the increased lifetime observed when using manganese oxide as a protective layer is a result of the inhibition of the growth of silicon oxide during the reaction.