Tetrakis(2-pyridyl)stannane (o-Py4Sn), which bears only weakly nucleophilic and Lewis basic pyridines, and a weakly acidic tetraaryltin moiety, was found to efficiently catalyze the reaction between acetic anhydride and alcohols. The reaction rate measurements using 1-phenylethanol show the catalytic activity of o-Py4Sn to be up to 20% of that of 4-(dimethylamino)pyridine (DMAP) and more than 100 times that of pyridine alone. Furthermore, the reaction using (t-BOC)(2)O was found to be comparable to that with DMAP, with o-Py4Sn being more selective. Thus, a highly efficient cooperative effect is operative with o-Py4Sn.