The adsorption of pyridine, carbon dioxide (CO2), and formic acid (HCOOH) on various types of surface sites of ZrO2, vacant sites (for example: bare surface Zr4+O2- ions), and those modified by terminal (t-) and bridged (b-) OH as well as t- and b-methoxy (OCH3) groups, has been studied by infrared (IR) spectroscopy. The selective reaction of CO2 with the t-OH group at 213 K and the adsorption of pyridine to replace the t-OH group on ZrO2 at 373-573 K confirms that t-HO-Zr site possesses acidic and basic properties. Moreover, the nucleophilic substitution adsorption of pyridine occurs more actively at the t-HO-Zr site than that at the vacant t-site on ZrO2. At 523 K, HCOOH reacts with basic t-OH or t-OCH3 species before the b-OH or b-OCH3 species. The selective reaction of HCOOH with t- and b-OCH3 groups on ZrO2 disappears at 573 K. The high activity of t-HO-Zr sites is attributed to relatively stronger Lewis acidic sites generated by releasing t-OH groups in the adsorption, and is also related to the high reactivity of t-OH groups, The Zr ions or t-OH groups at t-HO-Zr sites can play different roles in the adsorption of HCOOH, CO2, and pyridine, leading to its distinguishable features from those on vacant and b-OH sites. On the other hand, the OCH3 species at 573 K is supposed to be movable during the adsorption, resulting in the disappearance of the difference in reactivity of t- and b-OCH3 groups in the adsorption of HCOOH to replace OCH3 on ZrO2.