Interrelation has been investigated between the surface tension of a graphitizing inoculant and the efficiency of inoculation of grey iron SCh20. The results show that ferrosilicon with strontium, barium and zirconium is of elevated graphitizing capacity for lamination-graphite irons. The study of properties of irons and inoculants suggests the correlation between the behaviour of the casted metal yield strength and the surface tension and temperature coefficients for liquid inoculants.