Porous alumina films, prepared by anodization of pure aluminum (Al) thin film deposited on SiO2/Si substrate, has been fabricated and characterized. Constant voltage and constant current anodization in two-electrode cell configurations were performed. Electro-oxidation of Al in the voltage range of 1-90V was explored using the three electrolytes: 1M sulfuric acid (1-22V), 0.3M oxalic acid (1-70V) and 0.75M phosphoric acid (60-90V). The temperature dependence of the i-V characteristics and the properties of the porous structures are ascertained. An explanation for the difference in current density at same voltage for different electrolytes. The kinetics and mechanistic aspects of Al anodization are discussed.