A quantum mechanical study of the potential energy surface for the HNCS dimer is reported. The calculations were performed using DFT and ab initio MP2 methods. The most stable is a cyclic form with a double N-H center dot center dot center dot S interaction and the interaction energy in the range of 16.91-18.92 kJ mol 1. An open HNCS dimer bound by the N-H center dot center dot center dot N hydrogen bond is by ca 3.3-5.1 kJ mol (1) less stable. Experimental FTIR matrix isolation studies of HNCS/N2 system show that exclusively less stable open dimer is formed in solid nitrogen. Possible reasons for the observed discrepancy between theory and experiment are discussed. (C) 2016 Elsevier B.V. All rights reserved.