The heats of formation at 298.15 K of important atmospheric sulfur species were calculated using a high level of electronic correlation, CCSD(T), extrapolated to the complete basis set limit. Our results for SH, CH3SH, CH3S, CH3SO and CH3SO2, are, respectively, 34.4, -5.3, 29.7, -16.8 and -53.1 kcal mol(-1). By carefully choosing the chemical reactions, this investigation reports the most accurate DeltaH(f)(0) values available to date for these species. (C) 2002 Elsevier Science B.V. All rights reserved.