The structural quality of induction thermal plasma grown-SWCNTs synthesized through the injection of five different powder mixtures containing 87.2commercial carbon black/2.6Ni/2.6Co/7.6Y2O3 (wt%) with variable sulfur content of 0.02, 0.6, 1.1, 2 and 2.5 (wt%) in carbon black was investigated using Raman spectroscopy. The results showed an increase in G/D intensity ratio with sulfur content up to 2.0% implying higher structural quality of SWCNTs followed by reduction of intensity with 2.5%. The equilibrium composition of the mixtures as a function of temperature calculated using FactSage thermo-chemical software revealed a lower end temperature of total gas phase as a result of the sulfur addition and the heat related to the formation of Y 2 S 3 solid phase which eventually increases the structural quality of SWCNTs. However, the higher amount of dissolved sulfur in the liquid solution of metallic catalysts for the mixture with 2.5% sulfur can results in the poisoning effect.