The composition of photochemical native oxides grown on Hg1-xCdxTe (x=0.3) has been studied using x-ray photoelectron spectroscopy (XPS) and Rutherford backscattering spectroscopy (RBS). By analyzing and comparing the results of the XPS and RBS depth profiles, a simple method of multiplying the XPS raw counts has enabled a realistic XPS depth profile to be obtained without having to directly account for sensitivity factors or preferential sputtering of elements. Photochemical oxides grown in O-2 ambients were found to have a Hg rich surface layer in addition to a higher Hg concentration throughout the oxide film when compared to layers grown in an N2O ambient. For both growth processes, the bulk oxide regions had Cd/Te ratios in excess of that for the underlying mercury cadmium telluride (MCT) substrate and concomitantly lower Hg/Te ratios. Comparisons with other work indicate that the photochemically grown oxides are quite similar to anodically grown oxides in terms of oxide /MCT interface widths and oxide compositions.