An in-situ modulated photocurrent technique to study kinetics of dye adsorption and to determine binding constants of dye molecules on the TiO 2 surface is presented. An AC-photocurrent signal is measured, when a TiO2 electrode is in contact with the dye bath, containing an inert salt for increased conductivity, upon excitation with on/off modulated light. This method provides relatively rapid results and is very useful for comparative studies. Organic dyes (D149, D5, D35) and ruthenium complexes (N719, Z907, black dye) were investigated and the effect of a coadsorbant in the dye bath (deoxycholic acid) was also analyzed. © 2013 Elsevier B.V. All rights reserved.