Complexes containing cobalt and carbon monoxide ligands, CO releasing molecules(CORMs), have the potential of anti-tumor and anti-inflammatory. In this paper, three hybrid CORMs 1-3 were synthesized and tested for their toxicology in vivo and bioactivities. The results suggest that the complexes have a long half-life in the range of 43-53 min; their oral LD(50) to mouse are between 1 500 mg·kg(-1) and 5 000 mg·kg(-1). After the successive administration, complex 1 exhibited a toxic activity in rats’ liver, and induced an injury to liver cells. Complex 1 had a strong growth inhibition activity(IC(50) 36.20 μmol·L(-1) and 39.25 μmol·L(-1)) in both He La cells and Hep G2 cells, complex 2 displayed a lower activity in the inhibition of He La cells proliferation than the control 5-FU(IC(50) 114.19 μmol·L(-1)), but had a higher activity in the inhibition of Hep G2 cells than the control 5-FU(IC(50) 171.34 μmol·L(-1)). The anti-inflammatory study suggests that all of them reduce intracellular nitrite level, complexes 1 and 2 have a stronger activity than complex 3. Their anti-inflammatory activity attributes to the CO molecules of the CORMs, which was confirmed by comparison with the corresponding ligand.