Cuprous oxide (Cu2O) thin films were prepared via a one-step chemical bath deposition (CBD) approach. The prepared samples were preferentially orientated along the [2 001 direction, with a 52 nm crystallite size. The photocatalytic activities of the Cu2O thin films were evaluated by the degradation of methyl orange (MO) under visible light irradiation and monitored using a UV-vis spectrophotometer. The results confirmed that the photodegradation efficiency was dependent on several parameters, such as the amount of H2O2 and the pH of the MO solution. The optimum amount of H2O2 and the pH of the MO solution were determined to be 113.75 mu l and 5, respectively. A kinetic study had been performed, and the degradation kinetics was observed to follow a pseudo-first order kinetics model. The mechanism responsible for the enhanced photocatalytic activity of the Cu2O thin films in the presence of H2O2 was explored in detail. In recyclability tests, the prepared Cu2O thin film photocatalysts exhibited high photocatalytic activity, along with the morphological and orientational transformation. Interestingly, the photodegradation efficiency of the subsequent cycles was higher than the first cycle, which was due to the large specific surface area of the morphology-transformed photocatalyst. (C) 2013 Elsevier B.V. All rights reserved.