The control of unspecific adsorption of proteins to natural and technical surfaces plays an important role in biology and also for many applications. Organic model surfaces, e.g., self-assembled monolayers, are often used to identify fundamental surface and/or protein properties that rule protein adsorption. Some techniques involved in biointerface research require the use of heavy water, e.g. neutron scattering techniques. Also in NMR studies D2O is the solvent of choice when focusing on biomolecular and hydration dynamics. So far several studies have been concerned with the characterization of the unspecific adsorption of proteins from normal water buffers. In the present work, we report a comparison of the unspecific protein adsorption from normal and heavy water buffers. So far it has been assumed that the surface kinetic of the unspecific adsorption is unaffected by the substitution of water by D2O. However, for the four proteins investigated here, this assumption does not hold. The ratio kH/kD of the adsorption rate constants of the different buffer conditions describe the strength of the isotope effect. We have measured ratios between 1.0 and 2.6, indicating that the adsorption kinetics are strongly affected by a H2O-D2O substitution.