The continued reduction in the head-disk separation of magnetic data storage systems and the corresponding increase in the frequency of head-disk contacts will place severe stress on the lubricant and overcoat used to protect the surfaces of magnetic media. With decreasing fly heights, environmental conditions such as temperature and humidity that influence the lubricant-overcoat interactions become increasingly important to the tribological performance of the head- disk interface. It is essential to obtain a fundamental understanding of the molecular interactions at the lubricant-overcoat interface in order to maintain the reliability of future hard disk drives. The coadsorption of model fluoro alcohols and fluoro ethers with water was studied to gain a fundamental understanding of the effects of humidity on the bonding of perfluoropolyalkyl ether (PFPE) lubricants to amorphous hydrogenated carbon (a-CHx) overcoats. Temperature-programmed desorption experiments were performed using 2,2,2-trifluoroethanol (CF3CH2-OH) coadsorbed with water and perfluorodiethyl ether [(CF3CF2)(2)O] coadsorbed with water. The results indicate that the presence of water increases the desorption energy of CF3CH2OH on the a-CHx overcoat but decreases the desorption energy of (CF3CF2)(2)O on a-OHx overcoats. The implication of these results is that there is a net increase in the mobility of PFPE lubricant films when exposed to humid environments.