Two new d-element compounds, [Co(H2O)(6)](Detba)(2)center dot 2H(2)O (1) and [Ni(H2O)(6)](Detba)(2)center dot 2H(2)O (2) (HDetba - 1,3-diethyl-2-thiobarbituric acid) were synthesized and characterized by single-crystal and powder Xray diffraction analysis, TG-DSC and FT-IR. Structural analysis revealed that (1) and (2) are discrete structures, in which M2+ ion (M = Co, Ni) is six-coordinated by water molecules and it forms an octahedron. The outer-sphere Detba ions and H2O molecules participate in O-H center dot center dot center dot(O/S) intermolecular hydrogen bonds which form the 2D layer. Thermal decomposition includes the stage of dehydration and the following stage of oxidation of Detba with a release of CO2, SO2, H2O, NH3 and isocyanate gases. (C) 2016 Elsevier B.V. All rights reserved.