Thin films of tantalum oxide (Ta₂O₅) were formed electrochemically on tantalum electrode in several electrolytes at different applied voltages. The particle and pore sizes of oxide films were various depending upon the electrolytes. The thickness and structure of electrochemically grown oxides were examined using Z-ray photoelectron spectroscopy (ZPS), SEM, photoluminescence (PL), electroluminescence (EL) and cyclic voltammetry (CV). EL emissions of rare earth metal Tb^{3+ and organic Ru(bpy)₃2+ incorporated-Ta/Ta₂O₅ electrodes in aqueous solutions were observed. Since new EL emission energies are smaller than the band gap of 4.1 eV of Ta₂O₅, the resulting emissions are considered to be generated from surface states at the oxide band gap region. Incorporated inorganic and organic species are supposed to act as the luminescence centers for free electrons and holes. Since the emission spectra depend upon the incorporated chemical species and their concentrations, metal oxide films can be used for phosphor layers and analytical sensing probes by the controlled introduction of the label materials to produce surface states.}