Interfacial force microscopy is a novel technique for imaging and quantitative determination of the mechanical properties of a material such as elastic modulus, hardness, etc., with nm spatial resolution and nN force resolution. Due to the extreme pressures generated during probe-surface contact (many GPa), passivation of the chemical interactions, specifically adhesion, between the parabaloidal tungsten probe tips (radii 35 < r < 200 nm) and the substrate under investigation is often required. Convenient and effective protective monolayers are not generally available for many substrates; and it is necessary to develop; a general procedure for passivation of the tip. We have derivatized tungsten(100) surfaces with the silane coupling agent (octadecyltrichlorosilane, OTS) and applied the same techniques to nm-scale tungsten tips. Force versus displacement (f-d) curves were recorded for the following tip-Substrate interactions: underivatized tungsten tip against underivatized Au(111) surface, underivatized tungsten tip against derivatized Au(111) surface (C-18 thiol SAM), and derivatized tungsten tip (OTS) against underivatized Au(111). The data clearly show that the OTS derivatized tips were passivated against adhesive contact even at pressures of many GPa; thereby demonstrating the stability necessary for use in nanoindentation experiments.