Processes for converting a hydrocarbon reactant into an alcohol compound and/or a carbonyl compound are disclosed, and these processes include the steps of forming a supported chromium catalyst comprising chromium in a hexavalent oxidation state, irradiating the hydrocarbon reactant and the supported chromium catalyst with a light beam at a wavelength in the UV-visible spectrum to reduce at least a portion of the supported chromium catalyst to form a reduced chromium catalyst, and hydrolyzing the reduced chromium catalyst to form a reaction product comprising the alcohol compound and/or the carbonyl compound. The supported chromium catalyst can be formed by heat treating a supported chromium precursor, contacting a chromium precursor with a solid support while heat treating, or heat treating a solid support and then contacting a chromium precursor with the solid support.