We report the photoelectrochemical characteristics of some biologically used dye: Bromophenol, Ponceau 5, Sudan IV, Giemsa, and Acridine Orange as sensitizers. The J(SC) from 2.5 to 0.47 mA cm(-2) with the order Bromophenol > Ponceau S > Sudan IV > Giemsa > Acridine orange, the V(OC) from 642 to 384 mV, the fill factor (FF) from 0.61 to 0.40, and P(max) from 855 to 84 mu W cm(-2) were obtained from the DSSCs sensitized with these metal free organic dyes. Among these dyes, Bromophenol gave the best performance as sensitizer with maximum current, which is due to the better interaction between the hydroxyl groups of the dye on the surface of ZnO porous film. Incident photon-to-current conversion efficiency (IPCE) achieved with the use of these dyes follows the order Ponceau S > Sudan IV > Bromophenol > Giemsa > Acridine orange. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.