Protein adsorption on biomedical CoCrMo alloys plays a crucial role in biocompatibility, corrosion and wear properties of implants. So far, protein adsorption was studied only on passive CoCrMo alloys above the open circuit potential. In this work the adsorption of Bovine Serum Albumin (BSA) under cathodic conditions was investigated using a combination of Electrochemical Quartz Cristal Microbalance (EQCM) and X-Ray Photoelectron Spectroscopy (XPS) surface analysis. Results show that cathodic polarization yields larger BSA adsorption than what reported at passive potentials. The involved adsorption mechanism is related to the electrochemical controlled reduction of BSA. (C) 2015 Elsevier Ltd. All rights reserved.