The further improvement of desulphurization plants is an important task not only with a view to procedure technology but also economically. The aim of the optimization is mainly the adaptation of FGD plants to changing lignite qualities, the safe adherence to the required gypsum qualities and the reduction of the energy requirement (operating costs). Findings were compiled from many studies that, among others, concern the effects of adipic acid addition on the adsorbent, the retention behaviour and the gypsum produced. On the basis of this experience, the use of adipic acid was also tested in the FGD facilities of the Frimmersdorf power plant.