A series of alumina-supported Co–Mo samples prepared by the wet impregnation method have been used as catalysts for the synthesis of single-walled carbon nanotubes (SWNTs) by chemical vapor deposition (CVD) using CH4 at 900 °C. The mass ratio of the bimetallic catalyst with a composition of Co:Mo:Al2O3 has been demonstrated to play an important role in the formation of the single-walled carbon nanotubes obtained. In addition, the selection of solvent to disperse the Co–Mo/Al2O3 catalysts has a significant effect on the resulting quality of the carbon nanotubes produced.