The kinetics of autoxidation of sulphur(IV) in acetate buffered aqueous suspensions of limestone powder in the condition [S(IV)less than or equal to 1 x 10(-3) mol dm(-3) obeys the rate law which is first order in each of [limestone] and [S(IV)] and inverse first order in [H+]. On the other hand, in the condition [S(IV)]> 1 x 10(-3) mol dm-3 a different kinetics rate law which is first order in [limestone], second order in [S(IV)] and inverse first order in [H+] is obeyed. The calculations indicate that a slurry containing 1.0 g dm(-3) limestone will remove 90% of dissolved aqueous SO2 (1 x 10(-3) mol dm(-3)) in less than a minute at pH 6 and 40 degrees C.