Ammonia decomposition over Fe-based catalysts is a typical structure sensitive reaction, and the shape-controlled synthesis of Fe nanoparticles based on catalytic chemical vapor deposition (CCVD) method appears to be an effective method toward enhanced catalytic activity. The objective of this work is to understand effects of the reaction parameters on structural and textural properties of the resultant Fe catalysts and thus catalytic ammonia decomposition performance. The as-obtained catalysts are characterized by multiple techniques (N-2 physisorption, XRD, SEM, TEM, and Raman spectroscopy). Both the morphology and location of Fe nanoparticles are found to strongly depend on the partial pressure of H-2 as well as the growth time of CNFs. The long polyhedron shaped Fe nano particles on CNFs exhibit the highest activity among the prepared catalysts, which are relatively higher than the activities of the reported Fe based catalysts. The possible explanation for the good catalytic performance was proposed. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.