In this work, a mathematical model was developed for the prediction of packed-bed reactor behavior for CaO+CO2 reaction based on the random pore model. A natural limestone and a modified sorbent using acetic acid washing were used for the experiments. The performances of these sorbents were initially determined using a thermogravimeter analyzer. Then, the reaction was accomplished in a packed-bed reactor for obtaining CO2 breakthrough curves and investigation of model predictions. This model was able to successfully predict the effect of process conditions and solid texture on the breakthrough curves of the packed-bed reactor.