The structure of the title compound, [Co(II)(C(2)H(8)N(2))(3)]SO(4), the cobalt example of [M(C(2)H(8)N(2))(3)]SO(4), is reported. The Co and S atoms are located at the 2d and 2c Wyckoff sites (point symmetry 32), respectively. The Co atom is coordinated by six N atoms of three chelating ethyl-enediamine mol-ecules generated from half of the ethyl-enediamine mol-ecule in the asymmetric unit. The O atoms of the sulfate anion are disordered mostly over two crystallographic sites. The third disorder site of O (site symmetry 3) has a site occupancy approaching zero. The H atoms of the ethyl-enediamine mol-ecules inter-act with the sulfate anions via inter-molecular N-H⋯O hydrogen-bonding inter-actions.