The kinetics of the sulfation and carbonation reactions of the sorbent Ca(OH)(2) were investigated in an isothermal packed-bed reactor for the application to the flue gas desulfurization process at low temperatures. The reaction temperature was analyzed at three levels: 55, 65 and 75 degreesC; the relative humidity in the range between 40 and 70% and the sorbent load in the bed ranging from 200 to 600 mg. The experimental SO, breakthrough curves obtained were simulated and fitted to kinetic models according to least-squares minimization procedures by means of a commercial package for solving systems of PDEs. The sulfation and carbonation kinetics were described by a two parameters non-ideal adsorption model, considering a scheme of simultaneous reactions. The influence of the temperature and the relative humidity, was fitted by the kinetic parameters. The sorbent utilization profiles along the bed for sulfation and carbonation were also simulated, being the conditions at the inlet of reactor a good estimation of the sorbent activity at conditions prevailing in low-temperature desulfurization processes.