A homologous series of carboxylic acid monolayers was deposited on glass and steel surfaces by the Langmuir-Blodgett technique, and the resulting films were characterized by infrared reflection-absorption spectroscopy, X-ray photoelectron spectroscopy, and contact angle measurements. The friction and durabilities of the well-ordered, close-packed monolayer films on both substrates were evaluated using a reciprocating sliding apparatus, and the results were related to carboxylic acid chain length and monolayer film density. For even-numbered, straight chain carboxylic acids with 12-26 carbon atoms, the friction was found to be independent of the acid chain length and the surface density of the monolayer, but the durabilities increased with each. Durabilities on glass were two orders of magnitude greater than those on steel.Presented at the 47th Annual Meeting in Philadelphia, Pennsylvania May 4-7, 1992