The corrosion and tribocorrosion behaviour of a high carbon CoCrMo alloy sliding against alumina in simulated body fluids under potentiostatic conditions was investigated. The electrochemical behaviour of the sample in two electrolytes at different potentials (-1 V-Ag/AgCl, -0.5 V-Ag/AgCl, +0.05 V-Ag/AgCl, +0.5 V-Ag/AgCl and +0.75 V-Ag/AgCl) was studied by means of electrochemical impedance spectroscopy (EIS). The effects of solution chemistry and applied potential on the wear volume and anodic current were determined. Result shows that wear of CoCrMo alloy is negligible under cathodic and in the cathodic-anodic transition and considerably increases in the passive domain. Third body behaviour depends on surface chemistry which also varied depending on solution chemistry and electrochemically applied potential thus, modifies the tribocorrosion rate of CoCrMo alloy. (C) 2010 Elsevier Ltd. All rights reserved.