Electrochemical properties and electron transfer processes of biopolymers such as metal proteins or enzymes have been studied extensively, since it provides us important information to understand the redox system in biosystems. However, for example, it is not easy to obtain the reversible electrochemical response of superoxide dismutase (SOD) which dispropornations superoxide to molecular oxygen and hydrogen peroxide catalytically. Recently, electrochemical properties of various types of SODs have been reported using the so called self-assembled monolayer-modified electrodes or other type of functional electrodes. However, the results reported are not necessarily in good agreements. The authors introduce the modified electrode system for CuZnSOD reported by other research groups and describe the redox response of various SODs including CuZnSOD studied by our research group in this article.