Infrared spectroscopy has been used to study the chemisorption of pentamethylantimony, SbMe(5), on silica. For temperatures of activation from room temperature to 1000 degrees C, a single chemisorbed product is formed, =SiOSbMe(4). The hydrogen-bonded silanols react to completion faster than the isolated silanols. Unlike other reactive metal-alkyl compounds, there was no evidence for a significant reaction with siloxane sites, The chemisorbed species do not react with water vapor at room temperature or at 100 degrees C. However, upon heating under vacuum to 250-300 degrees C it decomposes to yield surface SiOMe groups and gaseous SbMe(3). Finally, the silanol groups can be regenerated when surfaces SiOSbMe(4) reacts with gaseous HCl to yield SbMe(4)Cl, the reaction being SiOSbMe(4) + HCl --> SbMe(4)Cl + SiOH.