This contribution deals with the self assembling of a terpolymer on titanium oxide (TiO2) surface. The polymer structure was obtained by polymerization of different methacrylates, i.e., alkyl-phosphonated, butyl and PEG methacrylate, in the presence of it chain transfer agent. The resulting PEG-poly(alkyl phosphonate) material, characterized mainly by SEC and NMR, self-organized at the interface of TiO2. AR-XPS demonstrated the binding of phosphonate groups to TiO2 substrate and the formation of a PEG-brush layer at the Outermost part of the system. The stability of this terpolymer adlayer, after exposure to solutions of pH 2, 7.4, and 9 up to 3 weeks, was evaluated quantitatively by XPS and ellipsometry. We demonstrated in overall stability improvements of this coating against desorption in contact with aqueous solutions in comparison with reference self-assembly systems. Finally, the PEG-terpolymer adlayer proved to impart to TiO2 substrate antifouling properties when exposed to full blood serum.