A reaction kinetics experiment for the chemical engineering undergraduate laboratory course was developed in which in-situ Fourier Transfer Infrared spectroscopy was used to measure reactant and product concentrations. The kinetics of the hydrolysis of acetic anhydride was determined by experiments carried out in a batch reactor. The results compared very favorably with reported pseudo-first-order kinetics for this irreversible reaction. The resulting rate expression was used to predict the performance of a semibatch reactor.