The effects of sulfur concentration in liquid iron on mineral layer development between coke and iron as coke dissolves in a 2 mass % carbon-iron liquid have been investigated at 1500°C. Initial sulfur in iron concentrations used ranged from 0.006 to 0.049 mass %. Key findings include that the two stage dissolution behavior exhibited in the carbon transfer from coke to iron as reported in a previous study by the authors, at low initial sulfur in iron contents, was also apparent at the higher values used in this study. This two stage behavior was attributed to a change in the mineral layer density, as a result of changes in mineral morphology at the interface. In addition to confirming the two stage behavior of the carbon transfer kinetics at the higher sulfur concentration in iron levels, it was also found that after a period of time a solid calcium sulfide layer formed on the mineral layer. The sulfide layer formed after approximately 40 minutes and the proportion of sulfide in the mineral layer increased with increased experimental time and initial sulfur concentration in iron. It was usually found at the iron side of the mineral layer and associated with calcium enriched calcium aluminates. Thermodynamic analysis of this layer confirmed that the sulfide is stabilized as the mineral layer is enriched by calcium.