Se-catalyzed disproportionation of bisulfite (HSO3-) is a facile and potential wet flue gas desulfurization. In this paper, the kinetics and mechanism of Se-catalyzed disproportionation of HSO3- were systematically investigated: The Se-catalyzed disproportionation of HSO3- is found to be pseudo-first-order with respect to the HSO3- and Se concentrations, and is zeroth-order with respect to the initial pH value. More, importantly, the kinetics of Se-catalyzed disproportionation of HSO3- can be divided into two stages, i.e., a rate-controlling stage and an acceleration stage. In the rate-controlling stage, the reaction rate is slow and the intermediate HSeSO3- forms. This intermediate is decisive to accelerate the HSO3- disproportionation, and thus, it plays an important role in the Se-catalyzed process. Furthermore, a kinetic equation is determined according to the results: r(0)= k(1)[HSO3-](0.94)[Se](1.13), where k(1) = (10.88 +/- 0.04) X 10(-2) M-1.07.min(-1). This kinetics prediction model is fitted well with the experimental data, indicating that this model can satisfactorily describe the experimental kinetic data of Se-catalyzed disproportionation of HSO3-.