Water splitting can store sustainable energies in the form of fuel (H-2) and oxidant (O-2). However, the efficiency of H-2 production from the reaction is limited by the slow kinetics of the water oxidation. Herein the promising role of fluoride on water-oxidizing activity of nanolayered Mn oxide is reported. The effects were studied for water oxidation in the presence of cerium(IV) ammonium nitrate. These experiments showed that the treatment of nanolayered Mn oxide by potassium fluoride increases water-oxidizing activity of these oxides in the presence of cerium(IV) ammonium nitrate approximately two times. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.