Carbon nanotubes were synthesized over a series of Zn-containing Fe/alumina catalysts by chemical vapor deposition method at two reaction temperatures of 850 and 950 °C using methane as a carbon source. Catalysts were synthesized by keeping Fe concentration constant and varying Zn concentration to study the effects of Zn. The catalysts were characterized using X – ray powder diffraction and N2 adsorption – desorption methods which confirmed the successful synthesis of catalysts and metals particles were inserted in alumina pores. The synthesized Carbon nanotubes were tested by scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetry analysis (TGA) and Raman spectroscopy. SEM images showed that the diameter of nanotubes almost was decreased with increasing Zn content of catalysts. In Raman spectroscopy, two main bands related to the carbon nanotubes were observed. Further, TGA results revealed that the percent of synthesized carbon nanotubes were almost increased with increasing [Zn]/[Fe] proportions.