The effect of the internal morphology of polyacrylamide hydrogel as an electrolyte on the anodic oxidation of aluminum, which can be used for the rectification of current, was studied. Comparing with traditional electrolytes, the chemical reactions between the aluminum and the free ions (H+ and OH−) occur more effectively due to the trapping of the ions in hydrogel. Oxidation efficiency, and thus the rectification, can be tuned with changing the composition of the gel. We are able to observe very high values, that is, it was around 850 at an applied potential of ±7 V, for a specific swelling degree and concentration of the hydrogel swollen in water for the rectification ratio for aluminum/hydrogel/platinum sandwich configuration. Stability of the hydrogel used as filler was studied via swelling and drying experiments. No considerable change in the performance of the gel was observed upon multiple usages. Therefore, the polyacrylamide hydrogel can be a good candidate for constructing oxidation based rectifiers. POLYM. ENG. SCI., 55:406–413, 2015. © 2014 Society of Plastics Engineers