AbstractThe catalytic hydrolysis of phenyl esters — 3‐acetoxy‐N‐trimethylanilinium iodide (ANTI), 3‐nonanoyloxy‐N‐trimethylanilinium iodide (NNTI), andp‐acetoxybenzoic acid (ABA) — was conducted at 30°C in an aqueous system using polymer catalysts containing a phenylimidazole unit. The hydrolysis of ABA with a negatively charged polymer catalyst followed second‐order kinetics, whereas the catalytic hydrolysis of the cationic substrates proceeded according to MICHAELIS‐MENTEN kinetics. The cationic substrates appear to be bound at the polymer catalytic site by electrostatic forces when the polymer contained the imidazole and carboxylate functions. The substrate binding behavior of the polymer catalysts was explicable by considering the conformational characteristics of the catalytic site. NNTI showed a binding tendency greater than that of ANTI because of its enhanced hydrophobic character due to the long acyl chain. The presence of the carboxylate group at the catalytic site facilitates the intra‐complex reaction for