Adsorption experiments for benzotriazole, (BTAH) on the gamma-Al2O3 surface were carried out at 150 and 293 K. The thermal stability of the adsorbed layer was investigated. At low temperatures, adsorption results in the production of a thick condensed layer of BTAH. Strong intermolecular hydrogen bonds are observed. With increasing sample temperature, the BTAH molecules diffuse into the Al2O3 pore structure. Hydrogen bonding of the BTAH molecule specifically to isolated Al -OH groups is observed. Deprotonation of the BTAH molecule begins to occur through interaction, with the surface oxide anions near 300 K. As a result of such deprotonation-type interaction the production of associated surface OH groups and of the BTA(-) anion are observed. The BTA(-) anion is bound to the surface Lewis acid site via a nitrogen atom lone pair. Extensive thermal treatment (T = 573-623 K) causes decomposition of the adsorbed BTA(-) species, and modes related to the nitrogen ring disappear. After thermal treatment up to 873 K, IR spectroscopy detects weak and broadened features of aromatic molecules on the surface. Auger spectroscopy of the sample after this thermal treatment shows that nitrogen containing species have disappeared whereas carbon remains. Infrared features due to aromatic residues persist to higher temperatures (T = 873-1023 K).