FTIR spectroscopy has been used to investigate the surface interaction of TiO2 powder particles sensitized with two of the most efficient sensitizers, the mono-nuclear complex [RuL2(SCN)(2) and the tri-nuclear complex RuL2[mu-(CN)Ru(CN)L-2＇](2) {L = 4,4＇-dicarboxylic acid-2,2＇-bipyridine and L＇ = 2,2＇-bipyridine}, both having ligands substituted with carboxylic acid (-COOH) functional groups. C=O band peak frequency shifts of about 20 cm(-1) higher than that of bulk complexes and disappearance of the CN- and SCN- band vibrations were observed on derivative samples. The C=O shift was attributed to chemical adsorption of the dyes onto the oxide particles via ester-like binding between the carboxylic acid groups and the OH moieties on TiO2. Incident light-electricity conversion efficiencies approaching unity with the above two ruthenium-bpy complexes attached on transparent nanocrystalline TiO2 films were reported. The morphology and the surface characteristics of the films studied by AFM showed the presence of a fractal network of interconnected grains whose diameter were between 15 and 25 nm. The height distribution of surface features has a maximum around 60 nm. On such large surface area electrodes efficient adsorption of the Ru-bpy complexes via ester linkages leads to extremely high photoconversion yields.