Chlorophyll-a (Chi-a) assembled in hydrophobic domain by fatty acid with long alkyl hydrocarbon chain such as myristic acid (Myr), stearic acid (Ste) and cholic acid (Cho) modified onto nanocrystalline TiO2 electrode is prepared and the photovoltaic properties of the nanocrystalline TiO2 film by Chl-a are studied. Incident photon to current efficiency (IPCE) value at 660 nm in photocurrent action spectrum of Chl-a/Ste-TiO2, Chl-a/MyrTiO(2) and Chl-a/Cho-TiO2 electrodes are 5.0%, 4.1 % and 4.1%, respectively. Thus, the IPCE is maximum using Chl-a/Ste-TiO2 electrode. From the results of photocurrent responses with light intensity of 100 mW cm(-2) irradiation or monochromatic light with 660 mn, generated photocurrent increases using Chl-a/Ste-TiO2 electrode compared with the other Chl-a assembled TiO2 electrodes. These results show that the hydrophobic domain formed by stearic acid with long alkyl hydrocarbon chain is suitable for fixation of Chl-a onto TiO2 film electrodes and photovoltaic performance is improved using Chl-a onto Ste-TiO2 film electrode. (C) 2007 Elsevier Ltd. All rights reserved.