Abstract A rigorous, rate-based model was developed to simulate the regeneration of CO 2 in aqueous ammonia-based CO 2 capture process. The model was based on the Aspen RateSep module, which adopts the kinetic, thermodynamic and transport properties of the NH 3 –CO 2 –H 2 O system available in Aspen Plus V7.3. We compared the modelling results with those obtained from pilot-plant trials at the Munmorah Power Station, New South Wales, Australia. The results agreed reasonably well for all 30 cases considered, including the energy requirement for regeneration, stripping temperature, and ammonia concentration in the product. Using the validated model, we then further analysed the pilot plant results to gain insights into the CO 2 regeneration process.