Chlorophylls (Chls) are naturally occurring photosensitizers having an excellent visible and near-infrared light absorption property. Herein, we employ three Chl a derivatives as sensitizers in a TiO2-based photocatalytic system for H-2 evolution with ascorbic acid as the sacrificial reagent under visible light (lambda > 400 nm). The H-2-evolution activity of these Chl a derivatives depends on a carboxy group in the C3- and/or C17-substituent(s). The concentration of 1 mg/ml dye/Pt/TiO2 powder suspended in an aqueous solution with ascorbic acid as the sacrificial reagent gives the highest H-2-evolution rate. The fact that Chl-2 with a carboxy group on the C3 position of the chlorin macrocycle gives the highest H-2-evolution rate of 0.79 pnol h(-1) is ascribed to the lowest charge recombination rate between Chl-2 and TiO2 among all Chls investigated. This work provides us with important information in synthesizing more favorable molecular structure of Chl derivatives for the highly efficient photocatalytic H-2 evolution from water splitting. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.