A vitrinite and an inertinite of high purity were separated from New Zealand and Lingshi bituminous coals with similar sulfur content and metamorphic grade.The vitrinite and inertinite were pyrolyzed in a tube furnace reactor filled with highly purified argon at 300,500,700,1 000 ℃.The effect of temperature on the functional group content and organic sulfur form transformation was examined by Fourier transform infrared spectrum and X-ray photoelectron spectrum,respectively.Several interesting trends are observed;the organic sulfide content in the vitrinite is higher than that in the inertinite;thiophenic sulfur is normally the dominant organic component in vitrinite and inertinite char;the vitrinite has higher desulfurization rate than inertinite at the same temperature;the vitrinite has similar desulfurization rate at lower temperature;when the temperature is higher than 700 ℃,the vitrinite which has lower thermal stability has more efficient desulfurization.