In this study, electrocoating of polyaniline conducting polymer on aluminum and microstructure of coated surface were investigated before and after corrosion. The polyaniline coating was performed in oxalic acid solution by using cyclic voltammetry. During electrochemical investigation of coated surface, an anodic peak due to oxidation of polymer and a cathodic peak due to reduction of polymer were observed. Microstructure of coating surface was studied by using optical and scanning electron microscope (SEM). Microstructural investigation showed that polyaniline coating layer completely covered to aluminum surface and microstructure of polyaniline coating consisted of globular and complex grains structure for both conditions. Under the corrosion condition, the polyaniline coating was found to be stable and protective.