The title compound, (Et₄N) [Co(S₂CO)(S₂COEt)₂], and its chromium analogue have been prepared by nucleophilic attack of (Et₄N)(S₂COEt) on the parent tris(ethylxanthato)metal(III) complex in acetone solution, the structure of the cobalt derivative being confirmed by single-crystal X- ray structure determination; the structure was refined by least squares to a residual of 0.045 for 2306 'observed' reflections. Crystals are orthorhombic, P bca, a 17.303(8), b 16.970(6), c 16.052(6) Ǻ, Z 8. <Co- S> for the ethylxanthate ligands is 2.28₆ Ǻ, longer than in the parent tris(ethylxanthato)-cobalt(III) complex, while <Co-S> for the dithiocarbonate, chelated through the two sulphurs, is 2.25₁ Ǻ.