A direct resistance measurement method using two point probes has been used to measure the electrical resistance of ductile graphite cast iron produced at different thickness sections and over a wide range of temperatures.  The thermal conductivity of this type of cast iron was estimated using the Wiwedemen- Franze –Loranze Law.  It was found that smaller section thickness has lower thermal conductivity than medium and larger thicknesses.  This is due to the formation of compacted and degenerated ductile cast iron at higher section thicknesses.