A new cobalt(II) complex, [Co(H2O)(4)(nia)(2)](suc)center dot(H(2)suc) [nicotinamide = nia, succinate = suc(2-)], has been synthesized and characterized by elemental analysis, IR. TG-DTA and single-crystal X-ray diffraction. It contains [Co(H2O)(4)(nia)(2)](2+) complex cations, uncoordinated suc(2-) anios and H(2)suc species. In the complex cation the cobalt(H) ion is coordinated by four aqua and two nia ligands in a distorted octahedral geometry. The suc(2-) dianion acts as a counter-ion, while H(2)suc is present as a molecule of solvation. A three-dimensional network is formed by O-H center dot center dot center dot O and N-H center dot center dot center dot O hydrogen bonds. The title complex exhibits luminescence in the solid state at room temperature. The magnetism of the complex was studied over the temperature range 1.8 - 300 K.