Heterogeneous nucleation of nodular graphite at inclusions in ductile iron during eutectic solidification has been investigated. The experimental part of this work deals with casting of ductile iron samples with two different inoculants in four different thicknesses. Chemical analysis, metallographic investigation and thermal analysis of the specimens have been carried out. A numerical model [1] has been implemented and the results (i.e. cooling curve, cooling rate, nodule count and solid fraction) have shown a good agreement with experimental studies; following this, inoculation parameters in the model have been studied and discussed.