In the present study, differences in characteristics and catalytic activity towards CO hydrogenation of Co catalysts dispersed on alumina-silica bimodal pore supports were investigated. The various amounts of alumina were prepared by incipient wetness impregnation method, then calcined them in air. Then, consequently impregnated with the cobalt precursors. After calcination, the various samples were characterized using N[subscript 2] physisorption, XRD, SEM/EDX, TEM, TPR and H[subscript 2] chemisorption. CO hydrogenation (H[subscript 2]/CO = 10/1) was also performed to determine the overall activity and selectivity. It revealed that the size of Co oxide species depends on the amount of alumina in support and type of Co precursor. A wide range of variables including particle size, support interaction, and the alumina content can affect the kinetics of reduction. It was found that for the alumina-silica bimodal pore catalyst, the catalyst dispersed on the high alumina content support exhibited high activities due to high reducibility. With use of cobalt nitrate as Co precursor exhibited highest activities. The use of cobalt chloride as Co precursor exhibited lowest activities due to decrease in cobalt dispersion.