Time-of-flight molecular beam scattering techniques are used to explore the energy exchange, thermal accommodation, and residence time of HC1 in collisions with an OH-terminated self-assembled monolayer. The monolayer, consisting of 16-mereapto-l-hexadecanol (HS(CH2)(16)OH) self-assembled on gold, provides a well-characterized surface containing hydroxyl groups located at the gas-solid interface. Upon colliding with the hydroxylated surface, the gas-phase HC1 is found to follow one of three pathways: direct impulsive scattering, thermal accommodation followed by prompt desorption, and temporary trapping through HO--HCl hydrogen bond formation. For an incident energy of 85 kJ/mol, the HC1 transfers the majority, > 80%, of its translational energy to the surface. The extensive energy exchange facilitates thermalization, leading to very large accommodation probabilities on the surface. Under the experimental conditions used in this work, over 75% of the HC1 approaches thermal equilibrium with the surface before desorption and, for a 6 kJ/moI HCl beam, nearly 100% of the molecules that recoil from the surface can be described by a thermal distribution at the temperature of the surface. For the molecules that reach thermal equilibrium with the surface prior to desorption, a significant fraction appear to form hydrogen bonds with surface hydroxyl groups. The adsorption energy, determined by measuring the HC1 residence time as a function of surface temperature, is 24 +/- 2 kJ/mol.