Nanostructured anatase TiO2 electrodes surface modified with inorganic metal oxide clusters, i.e., phosphotungstic acid (PWA), was studied by XPS and spectroelectrochemistry. The surface modifiers were electroactive and could be addressed reversibly by changing the applied bias. The formation of new states in the electronic structure of TiO2 and the PWA was monitored by XPS using a novel preparation technique. The coloration efficiency of the deposit was about 20 cm(2)/C. Prolonged electrochemical cycling degraded the electrical contact between the PWA and the TiO2 surface.