With respect to the actual required removal efficiency of the conventional wet limestone flue gas desulfurization with spray absorber systems, a working theory was developed to improve the efficiency. This hypothesis was based upon the fact, that inside in a spraying tower there are differential ranges of mass transfer and the spray cannot have the highest removal efficiency in all these ranges. The research studies were conducted on a testing facility with a pilot scale spray tower. Using systems with high efficiency in separate ranges, it should be possible to optimise the overall removal performance. An absorber system was chosen, comprising a bubble column for the high SO2-concentration and a fine spray system for the low concentration. The result of experimental series shows that the bubble column was a qualified system for the high and lower loaded SO2 range. On the other hand the small dispersed spray could not validate the working hypothesis. The experiment with the serial bubble column and the spray shows at the lower loaded flue gas a full removal of SO2. In the high loaded case, it has the best removal performance of all experiments with reduced energy and suspension consumption.