Surface treatments on implants is the way to create surfaces with the desirable properties and morphologies improving therefore the implant’s interaction with the body. β-Ti-based alloys are well known for their biocompatible properties, high corrosion resistance and low toxicity. In this work we focus on the β-TiCuZr that is biocompatible and contains Cu, which is known for its antibacterial property, while its presence in high concentration can lead to toxicity [1]. Therefore, it is important to reduce Cu concentration from the sample surface. Dealloying technique can be used for surface treatment of β-TiCuZr based alloys. Dealloying is selective removal of one or more less noble element from an alloy using a corrosion mechanism [2]. An experimental investigation was performed to de-alloy Cu from TiCuZr based amorphous alloy using an acidic media. There are many studies concerning the dealloying of β-TiCuZr but studies concerning the early stages of this process are rather limited. Ab initio calculations were carried out, using density functional theory (DFT), in order to obtain a fundamental understanding of the dealloying mechanism of a biocompatible Ti 40 Cu 40 Zr 20 at% metallic glass surface under small molecules deposition. Several surfaces structures and configurations have been investigated resulting the rich in Cu terminated layer as the energetical favoured. In accordance with the experimental results of an amorphous Ti 40 Cu 40 Zr 20 structure, the surface structure that has been found to be energetically favoured is the agglomerated Ti and Cu configuration having mixed Zr atom’s first neighbourhood. The metallic character of the alloy is maintained throughout the surface while non-bonded 3d orbitals are observed, especially on Cu atoms, creating dangly bonds. The deposition of molecule seems to prefer energetically the position on top of a Ti atom, without interfering notably with the electronic properties of the system while some bonding states are observed on top of Cu surface atoms which might explain the dissolution of Cu atoms that is experimentally observed.