[Co(NH3)6]ClCO3 crystallizes in the cubic space group P21 3(No. 198)witha = 1000,5(2)pm, VEZ = 1001,4(3) · 106 pm3, Z = 4. Structural features are discrete [Co(NH3)6]3+, CO3 2- and Cl- ions, connected by N-H···O and N-H···Cl bonds. The site symmetry of the carbonate group is C3, but vibrational spectroscopy shows that the CO3 2- group is planar with local symmetry D3h.