Experimental and theoretical transient behavior of a recycle system were studied for a plug flow reactor with a mixing tank and a recycle line. The consecutive reaction chosen for experimental study was the hydrolysis of diethyl succinate through monoethyl succinate to succinic acid on a strong acid ion exchange resin at 50°C. Both realistic and simplified models were developed to simulate the transient behavior of the recycle system. The simplified model was more useful than the realistic model because analytical solutions could be obtained. The approach time to the steady state is presented for the recycle reactor.