The supported Co/SiO 2 and Co/active carbon (A.C.) catalysts were studied as heterogeneous catalysts in the liquid-phase hydroformylation of 1-hexene. The pore size of silica support significantly influenced the activity and selectivity of Co/SiO 2 catalysts in hydroformylation of 1-hexene. The silica supported cobalt catalyst exhibited the best hydroformylation reaction performance at 403 K, and catalytic activity for this kind of catalyst increased with the increasing initial reaction pressure. The addition of small amount of noble metal significantly improved the activity and selectivity for Co/SiO 2. The solvent effects for Co/SiO 2 and Co/A.C. catalysts in the hydroformylation reaction of 1-hexene were investigated and alcoholic solvents promoted the oxygenate formation significantly.