Flame offer potential for synthesis of carbon nanotubes in large quantities at significantly lower cost than that of other methods currently available. Catalyst can decide the produces category, structure, capability, etc. This study aimed to examine catalyst for carbon nanotubes synthesis. In this experimental, oxy-acetylene flame is used as the source of heat, and CO as the source of carbon. Nebulized Fe(CO)5 as catalyst gets straight, uniform, and long tubes while coated iron-aluminum compound as catalyst gets nanoparticles coated tubes, although these tubes are thin, long, and straight. Coated Fe(CO)5 as catalyst only can gets curly and short tubes, directly introduced into synthetic chamber gets particles, and Fe2O3 powder as catalyst mainly gets curly tubes. Although the tubes which iron-aluminum compound as catalyst are high capability, they must be purified before use while Fe(CO)5 as catalyst can gets smooth tubes.