Stable structures of nitrogen-rich sulfides SN4, N3SN4, and S(N-4)(m)(2-) (m - 1-4) were studied. Two of SN4, three of SN42+, two of SN42-, one of SN4- and two transition structures of the dissociation reactions of SN4 were obtained. Four stable species of N3SN4, and a transition structure of the dissociation reaction of N3SN4 were calculated. In the set of S(N-4)(m)(2-)(m = 2-4), the sulfur atom with large atomic radius and loose electron density allows it connect more nitrogen) clusters N-4 to form nitrogen-rich sulfides S(N-4)(m)(2-). SNx may be used as high energy-density material combining with opposite ion. (C) 2003 Elsevier Science B.V. All rights reserved.