The amount of water adsorbed on different centers on the surface of oxalic acid alumina films is a function of the anodizing voltage. It is decreased with increasing the anodizing voltage from 20 up to 50V, came up to maximum value at 20–30V and slightly increased at voltages above 50V. Water adsorption by oxide films formed at voltages below 50V can be due to the negative surface charge that is present on the alumina surface. The negative surface charge disappears in the films formed at voltages higher than 50V, and thus, the water is adsorbed on aluminum ions in a tetrahedral and octahedral environment. The correlation between anodizing conditions of aluminum in oxalic acid and the structure and composition of anodic alumina was established by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), thermogravimetric and differential thermal analyses (TG/DTA).