The experimental work for the depolymerization process of Bisphenol A polycarbonate pellets and CD/DVD wastes in a semicontinuous reactor and a novel nonstationary model to describe the process is presented. The different steps of the process to develop the model are analyzed thoroughly. The kinetics of the alkali-catalyzed methanolysis of polycarbonate was determined. The reactor and kinetic models were validated by a series of 21 experiments performed in a laboratory semicontinuous tubular reactor at isothermal conditions from 90 to 180 degrees C and pressures from 1.0 to 20.0 MPa in liquid phase, with and without NaOH concentrations of 1 X 10(-3) to 5 X 10(-3) kg/L, flow rates from 2.3 X 10(-3) to 10.2 X 10(-3) L/min, and CO2 molar fractions from zero to 0.374. The effects of temperature, pressure, catalyst amount, mass transfer (solvent flow rate), and CO2 addition in kinetics were investigated. (c) 2006 American Institute of Chemical Engineers.