The electrochemical behavior of LaNi3.55Mn0.4Al0.3Co0.75 material was investigated with the help of a cavity microelectrode. The cyclic voltammetry study versus the scan rate evidenced the formation of a passivation layer, which is characterized by a positive current during the cathodic sweep. The performances of the LaNi3.55Mn0.4Al0.3Co0.75 compound as a negative electrode for nickel–metal hydride (Ni–MH) battery can also be determined with the cavity microelectrode. It was shown that even in drastic potential sweep conditions, the material exhibits a very good reversibility during several thousands of cycles.