The photoelectrochemical behavior of colloidal hematite photoelectrodes, prepared by either hydrothermal or electrophoretic means and modified with Fe(III) based water oxidation catalysts and a compact blocking underlayer is discussed with regard to the electron/hole charge transfer and recombination kinetics. While the presence of an amorphous iron oxide catalyst allows for the trapping of photoholes in reactive states at interface with the electrolyte, the presence of a compact hematitic underlayer between the porous semiconductor and the FTO electron collector improves the selectivity of the back contact to electrons, thus reducing recombination due to accumulation of charge carriers within the film under illumination. A considerable improvement of the photoelectrochemical efficiency follows.