Ammonia synthesis using magnetic field provides a big challenge for new catalyst as compared to the catalysts used in Haber-Bosch's ammonia production. Apart from that, physical and chemical modification techniques play vital roles and are confined for carbon nanofiber supported iron catalyst preparation using incipient wetness impregnation. The found results indicate that the chemical (HNO3) and physical (thermal N2 gas flow) combination method of carbon nanofiber gives higher adsorption sites as defect sites and functional groups and lesser amorphous components than physical approach. This results in well-dispersed iron supported on carbon nanofiber with diameter size range of 10-50nm. © 2014 AENSI PUBLISHER All rights reserved.