The effect of addition of 0.05wt.% to 0.25 wt.% Ca,Zr,Al-FeSi alloy on in-ladle and in-mould inoculation of grey cast irons was investigated.In the present paper,the conclusions drawn are based on thermal analysis.For the solidification pattern,some specific cooling curves characteristics,such as the degree of undercooling at the beginning of eutectic solidif ication and at the end of solidifi cation,as well as the recalescence level,are identif ied to be more influenced by the inoculation technique.The degree of eutectic undercooling of the electrically melted base iron having 0.025% S,0.003% Al and 3.5% Ce is excessively high(39-40℃),generating a relatively high need for inoculation.Under these conditions,the in-mould inoculation has a more signif icant effect compared to ladle inoculation,especially at lower inoculant usage(less than 0.20 wt.%).Generally,the eff iciency of 0.05wt.% -0.15wt.% of alloy for in-mould inoculation is comparable to,or better than,that of 0.15wt.% -0.25wt.% addition in ladle inoculation procedures.In order to secure stable and controlled processes,representative thermal analysis parameters could be used,especially in thin wall grey iron castings production. The effect of addition of 0.05 wt.% To 0.25 wt.% Ca, Zr, Al-FeSi alloy on in-ladle and in-mold in gray cast irons was investigated. In the present paper, the figures are based on thermal analysis.For the solidification pattern, some specific cooling curves characteristics, such as the degree of undercooling at the beginning of eutectic solidification and at the end of solidifi cation, as well as the recalescence level, are identified to be more influenced by the inoculation technique. The degree of eutectic undercooling of the electrically melted base iron with 0.025% S, 0.003% Al and 3.5% Ce is excessively high (39-40 ° C), generating a relatively high need for inoculation. Unit of these conditions, the in - mold inoculation has a more signif icant effect compared to ladle inoculation, especially at lower inoculant usage (less than 0.20 wt.%). Generally, the eff iciency of 0.05 wt.% -0.15 wt.% of alloy for in-mold inoculation is comparable to, or better than, that of 0.15 wt.% -0.25 wt .% addition in ladle inoculation procedures.In order to secure stable and controlled processes, representative thermal analysis parameters could be used, especially in thin wall gray iron castings production.