Highly hydrophilic carbon dots (HCD) prepared by dehydration and oxidation of cellulose were used in preparation of hybrid heterostructures with alpha Fe2O3 in aqueous medium. The nanostructures were characterized by different techniques including XRD, Mossbauer spectroscopy, TG, HRTEM, FTIR, Raman, potentiommetry titration and cyclic voltammetry. The formation of a hybrid heterojunction was shown by determining the energy of the top of the valence band and the bottom of the conduction band through voltammetric measurements and electronic spectroscopy. These results indicate that the hybrid material exhibits Type II band offsets that are able to promote an efficient separation of photogenerated charges under irradiation of visible light. The photocatalytic activity of the heterojunction was evaluated in the photodegradation of indigo carmine dye. The high photocatalytic activity observed under visible light is discussed on basis of the coupling of the hybrid heterojunction band structure. (C) 2015 Elsevier B.V. All rights reserved.