Pack cementation is a well known method for creation of diffusional coatings at low or high temperatures. The coating of manganese on AISI 430 alloy is applied and the corrosion properties of the coating have been investigated by electrochemical impedance spectroscopy (EIS) method. For modeling of variables that influences the corrosion properties of the coating, Box-Behnken experimental design and response surface methodology (RSM) is employed. The variables included amount of manganese in pack cementation mixture, amount of ammonium chloride and annealing temperature. The corrosion properties of Mn-coated samples have been investigated in NaCl 3.5 wt% solution. The results of EIS tests prove that Box-Behnken design (BBD) and response surface methodology could effectively be applied for modeling of Mn diffusional coating properties.