[en] The electrochemical nature of three different acid solutions was examined and factors affecting the shape of the polarization curves were evaluated. Potentiodynamic polarization curves were obtained for 10% hydrochloric acid, 50% sulfuric acid-0.1 M ferric sulfate, and 10% chromic acid on a platinized platinum surface and on various nickel rich alloys. The polarization measurements were generally conducted at room temperature in hydrogen saturated solutions. However, several polarization curves were also measured in aerated solutions in order to determine the influence of oxygen on the electrochemical characteristics of each acid. Conclusions from this investigation are given