In this study, process Optimization has been applied to D-massecuite boiling, coolingrncrystallization, reheating and separation processes in MSF to minimize the high sucrose lossrnwith final molasses. Mother liquor purity and Purity drop were taken as response variables tornmeasure the performance of each process towards minimization of final molasses purity. DesignrnExpert-Response surface methodology was applied to statistically evaluate the data and to solvernoptimum values factors and response variables. Economical advantages of the processrnoptimizations were compared with the factoryâ€™s existing working norms. D- massecuite boilingrnoptimization has resulted in nutsch purity reduction of 0.53 units. Similarly, an increase inrnpurity drop of 0.80 (from 4.21 to 5.01) across cooling crystallizers was obtained at optimumrncooling time of 17.36h and temperature to 450C for the existing crystallizerâ€™s capacity. Therncooling experimental results have indicated that a purity drop of 6.37 units can be achieved ifrncrystallizer capacity of MSF increased so as to give cooling time of 34.5h and temperature ofrn440C. For the existing reheaters, the optimum reheating temperature was found to be 52.50Crnwhich gave a purity rise across reheaters of 0.530 against the value of 0.97 before optimizationrnand the optimum massecuite flow rate of 19t/h. From the centrifugal separation optimizationrnresult, the optimum spray water was found to be 6.3% massecuite giving a purity rise of 2.44rnacross centrifugal machines and DFW magma purity of 84.0. The overall effect of processrnoptimization was a reduction in final molasses purity by 1.43 units (from 34.86 to 33.43) for thernexisting capacity of cooling crystallizer which leads to annual saving of 1040.5 tons sugar,rnequivalent to 13,526,919 Birr. Additional saving of 12,334825birr/year is expected if enoughrncrystallizer capacity is installed for MSF.rnKey words: Final Molasses, Sucrose Loss, Purity, Purity Drop, Exhaustion, Response SurfacernMethodology