A RhH(CO)(PPh3)(3)-derived SiO2-tethered catalyst via a thiol ligand is not only quite effective and stable for cyclohexene hydroformylation under the milder conditions of 100 degreesC and 28 bar of equimolar CO and H-2 but also more active than the corresponding homogeneous catalyst. This catalyst has the advantage in resistance to rhodium leaching over homologous tethered catalysts via phosphine and amine ligands.