Palladacycle 1 catalyzes the methanolytic cleavage of N-methyl-N-(4-nitrophenyOthiobenzamide (4) via a mechanism involving formation of a Pd-bound tetrahedral intermediate (TI). The rate constant for decomposition of the complex formed between 1, methoxide, and 4 is 9.3 s(-1) at 25 degrees C; this reaction produces methyl thiobenzoate and N-methyl-4-nitroaniline. The ratio of the second-order rate constant for the catalyzed reaction, given as k(cat)/K-d, relative to that of the methoxide-promoted reaction is 3 x 10(8), representing a very large catalysis of thioamide bond cleavage by a synthetic metal complex.