The adsorption of lead naphthenate on the surfaces of metals oxides, and sulfides was investigated by means of x-ray photoelectron spectroscopy (XPS). Lead naphthenate physically adsorbs on all surfaces. It chemisorbs on surfaces with basic sites, such as oxides, sulfides, and metals treated in basic solutions before adsorption. The two states have distinct XPS spectra. Conditions of surface preparation that result in the formation of each state are described.