Copper alloys usually used in cooling circuits of industrial plants can be affected by biocorrosion induced by biofilm formation. The global objective is to study the influence of biomolecules adsorption, which is the first step in biofilm formation, on the electrochemical behaviour of 70Cu-30Ni (wt. %) alloy and the chemical composition of oxide layers. In this work, the chosen biomolecule was the bovine serum albumin (BSA, model protein) and electrochemical measurements performed after 1 h of immersion in static artificial seawater were combined to surface analyses. In the presence of BSA, the charge transfer resistance deduced from EIS data at Ecorr is higher, corresponding to lower corrosion current. Without BSA, two oxidized layers are shown by XPS and ToF-SIMS: an outer layer mainly composed of copper oxide (Cu2O redeposited layer) and an inner layer mainly composed of oxidized nickel, with a global thickness of ~30 nm. The presence of BSA leads to a mixed oxide layer (CuO, Cu2O, Ni(OH)2) with a lower thickness (~10 nm). Thus, the protein induces a decrease of the dissolution rate at Ecorr and hence a decrease of the amount of redeposited Cu2O and of the oxide layer thickness.