Thermodynamic feasibilities of four possible intermediates as Cl atoms, two compounds of C-Cl, C-O-Cl, and oxychlorides during carbochlorination process of Al2O3, Fe2O3, and SiO2 in fly ash have been evaluated by thermodynamic simulation using the FactSage software at atmosphere pressure as 0.77 atm over a temperature range from 673 to 1273 K. The formation of the intermediates and reaction routes in the carbochlorination process were revealed.