The fate of sulfur during carbonization at 3 degrees C/min of seven caking coals with carbon and sulfur contents of 80-88 and 0.55-1.8 mass%-daf, respectively, has been studied using a flow-type fixed-bed quartz reactor to examine its effect on coal fluidity in caking coal. Org.S transfers to H2S or tar-S from 200 to 350 degrees C, and FeS2 decomposes to H2S and FeS above 350 degrees C. The H2S formation rate exhibits two distinct peaks at 450 and 550 degrees C. The amounts of H2S that evolved and Org.S that remained in cokes often depend on carbon contents in raw coals. The maximum fluidity (MF), determined by the Gieseler plastometer method, appears at around 450 degrees C for all of the coals examined, and the values range from 1.1 to 4.1 log(ddpm). The MF value tends to decrease with increasing amounts of FeS2 or Org.S remaining in solid products up to 450 degrees C. Sulfur-containing compounds, such as elemental sulfur, FeS2, diphenyl disulfide and dibenzothiophene, added to caking coal adversely affect coal fluidity. (C) 2013 Elsevier B.V. All rights reserved.