The electrochemical behavior of ductile nickel aluminide has been examined in alkaline, acidic and neutral solutions. Conditions for passive behavior, as well as for passivity breakdown, have been defined. The experimental results are compared with those obtained with the pure constituent metals, Ni and Al. Pitting has been observed not only in chloride-containing solutions, but in sulfuric acid in a certain potential range. This pitting is believed to be caused by a potential-dependent transition from the passive to the active state. The corrosion resistance of nickel aluminide appears to be similar to that of pure nickel. © 1990.