Biofilms on metal surface in an aqueous environment is a complex electrochemical system. The heterogeneous electrochemical characteristics of biofilm/metal interface and local electrochemical techniques used for this purpose are discussed in this work. The techniques presented in this work include microelectrode, scanning vibrating electrode, the wire beam electrode method, and scanning electrochemical microscopy. Two potentially useful techniques, localized electrochemical impedance spectroscopy and scanning Kelvin probe force microscopy, are also discussed. The advantages and limitations of these techniques are summarized. A new approach: numerical simulation of micro-electrochemical heterogeneity of biofilm covered metals is introduced.