Inorganic membranes of alumina have been prepared by anodic oxidation of aluminium. The kinetics of the growth of alumina layer in phosphoric acid has been studied at four different temperatures, viz., 20, 30, 40 and 50 degrees C. The coating ratio, coating thickness, and weight of alumina formed at different time intervals, have been measured. The effect of formation current on the coating thickness has been elucidated. Separating the alumina layer from metal by specifically dissolving the later in bromine and methanol mixture, the surface structures of the oxide layer has been studied by scanning electron microscopy.