The title complex salt, [Ni(C(3)H(8)N(2)S)(6)](NO(3))(2), consists of an [Ni(Dmtu)(6)](2+) (Dmtu is N,N'-dimethyl-thio-urea) dication and two nitrate counter-anions. The Ni(II) atom (site symmetry ) is coordinated by the S atoms of six Dmtu ligands within a slightly distorted octa-hedral environment. The crystal structure is characterized by weak intra-molecular N-H⋯S inter-actions and by inter-molecular N-H⋯O hydrogen bonds involving the nitrate anion (site symmetry 3.). These inter-molecular inter-actions lead to the formation of two-dimensional networks lying parallel to the ab plane. The networks are linked via non-classical inter-molecular C-H⋯O hydrogen bonds, forming a three-dimensional arrangement.