‏‎the main purpose of this research was to:1.develop a coking model for thermal cracking of naphtha.2.study coke inhibition methods using different coke inhibitors.developing a coking model in naphtha cracking reactors requires a suitable model of the thermal cracking reactor based on a reliable kinetic model.to obtain reliable results all these models shall be solved simultaneously.for this purpose org reaction network was used and tuned by experimental data.the detailed mechanistic kinetic scheme in this network,involves over 542 reactions and 91 molecular and radical species.finally,a coking model with 24 coke precursors in five groups was obtained.regarding coke inhibition,different additives were studied. these compounds chemically interfere with the surface and gas phase reactions,thus preventing the build up of coke in the reactor.our experiments showed that the organosulfourous compounds such as dmds and disulfideoil can inhibt coke formation and co production.also results obtained from our experiments in thermal cracking of naphtha in the presence of triphenyl phosphine and triorto-tolyl phosphine showed that using these compounds results in lower coking rates in comparison with organosulfourous compounds.‎‏