Abstract: Nine organic acids including monoacid, diacid and hydroxycarboxylic acid were used as additives in a. c. etching of aluminum foil in hydrochloric acid medium. The results show,as reported in previous paper with additives of sulfuric acid that these additives are essential in formation of a compact etch film, which is broken through during each anodic cycle of the ac-current, thus a high density of etch pits and a large surface area magnification can be obtained. For a certain a. c. frequency there exists an optimum additive concentration C_m,the greater the first dissociation constant of the acid, the lower the C_m. C_m also decreases with increase of a. c. frequency. It is proposed, that the organic acid anion was competitively adsorbed with (Cl^-) ion, forming a buffer layer, which decreases the solubility of etch film. The effects of the concentration of hydrochloric acid, the current density of a. c. and the overall concentration of Cl^- ion on etching process were also discussed.