The contact angle measurement using the sessile drop method for characterizing surfaces is a very simple, cost effective and accurate method. For the purpose of characterizing an amphiphillic Ag nanoparticle film, an instrument called the goniometer was built. Different parts were assembled that were bought from various companies in order to construct this instrument. Using this home-built instrument, contact angles were measured. For water on Teflon, glass and a thin film of nanoparticles, the contact angles were 115 degrees, 17 degrees and 20 degrees with an uncertainty of ? 4 degrees, respectively. The theoretical values of these angles for water on Teflon and glass are 110 degrees and 14 degrees, respectively. Though the uncertainty was quite high for the instrument, it provided us with a clear understanding about the chemical nature of the surface.