A program for a model-based optimisation has been developed. The program contains two subprograms. The first one does minimising or maximising constrained by one original PLS-component or one equal to a combination of several. The second one does searching for the optimal combination of PLS-components, which gives max or min y. The program has proved to be applicable for achieving realistic results for implementation in the design of Portland cement with respect to performance and in the quality control during production.