Inoculation comparisons were made between Calcium-bearing FeSi75 and a new complex alloy tablet (CAT) inoculant to compare their effects on late inoculation. Thermal analysis was used to study the solidification behavior and how FeSi75 and the CAT inoculants affect graphite nucleation. Quick-cup addition rates for FeSi75 ranged from 0.1% to 0.3% while the CAT, was added in much smaller amounts, 0.01 to 0.03%. Thermal analysis of the base low sulphur iron (0.02 %S) was characterized by excessive eutectic undercooling. It was found that an addition of 0.03% of the CAT had inoculation efficiency comparable to 0.2% to 0.3% Ca-FeSi75 in reducing the level of undercooling, recalescence and the maximum recalescence rate. A greater negative peak of the first derivative at the end of solidification process, that would minimize micro-shrinkage tendencies, was also obtained.