Nanostructured anatase TiO2 electrodes surface modified with inorg. metal oxide clusters, i.e., phosphotungstic acid (PWA), was studied by XPS and spectroelectrochem. 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 prepn. technique. The coloration efficiency of the deposit was about 20 cm2/C. Prolonged electrochem. cycling degraded the elec. contact between the PWA and the TiO2 surface.