The formation and homogeneous photodecomposition of chromate(VI) ester are often overlooked during the studies of photocatalytic reduction of hexavalent chromium, Cr(VI), in the presence of sacrificial electron donors such as methanol. When photoexcited (lambda <= 525 nm), the chromate(VI) ester, formed by the spontaneous reaction of aqueous Cr(VI) with methanol, undergoes homogeneous stepwise decomposition to trivalent chromium, Cr(III). The addition of semiconductor photocatalysts, i.e., TiO2 and WO3, at relatively low concentrations (= 420 nm), suppression in the rate of Cr(VI) reduction was observed at all concentrations tested. Importantly, the work showcases the parallel but non-independent effects of homogeneous photodecomposition of chromate(VI) ester and its photocatalytic reduction over semiconductor photocatalysts. (C) 2017 Elsevier B.V. All rights reserved.