The present work compares the physicochemical properties of carbon nanofibers (CNF) and carbon nanospheres (CNS)-supported bimetallic cobalt and iron catalysts and their performance in the Fischer-Tropsch synthesis (FTS), at 523 K and 20 bar. Supports were characterized by N-2 adsorption-desorption, temperature-programmed reduction (TPR) and decomposition under He atmosphere (TPD-He), X-ray diffraction (XRD) and Raman spectroscopy. Catalysts were in turn characterized by inductively coupled plasma spectrometry (ICP), N-2 adsorption-desorption, TPR, XRD and transmission electron microscopy (TEM). Results showed that the bimetallic catalyst supported over CNF was highly active in the conversion of CO and H-2 to hydrocarbons and selective towards gasoline and kerosene fractions. On the other hand, catalyst supported over CNS presented small and well-dispersed metal particles-which strongly interacted with the support and, as a consequence, promoted the reactants conversion in a lesser extent and favoured the growth of hydrocarbon chains. (C) 2015 Elsevier B.V. All rights reserved.