1. A method for determining the amounts of reagents required in the desulphurization of a hot metal batch, the method being characterized by the following steps. a) acquiring historical values ( 22 ) of process parameters ( 20 ); b) selecting training data ( 24 ) from said historical values of process parameters to represent normal operation of a desulphurization station; c) developing a multivariate statistical model ( 26 ) corresponding to normal operation of the desulphurization station with input from said training data; d) acquiring on-line values of process parameters ( 40 ) during operation of the desulphurization station; and e) calculating an output vector ( 44 ) to predict required amounts of desulphurization reagents using said multivariate statistical model.