Abstract:  Large-scale insitu synthesis of Fe-filled carbon nanotubes was achieved by chemical vapor deposition (CVD) with anhydrous FeCl₃ as floating catalyst precursor and ethylene as carbon source. The effects of catalyst and carrier gas were studied. The as-grown products were characterized using SEM, TEM, XRD, Raman, and vibrating sample magnetometer techniques. It has been found that for the floating CVD technique, anhydrous FeCl₃ is a good yet cheap catalyst precursor that is better than the traditional ferrocene catalyst in terms of the purity and filling ratio of the Fe-filled carbon nanotubes produced. The superparamagnetic property of the carbon nanotubes was also demonstrated by vibrating sample magnetometry.