The effect of morphology and structure of graphene nanosheets (GNS) and carbon nanotubes (CNT) as support on the stability of cobalt catalyst for Fischer-Tropsch synthesis (FTS) was investigated using a fixed bed micro-reactor.15.0 wt.% of cobalt was loaded on the supports by impregnation method. The deactivation of the two catalysts was studied at 220 degrees C, 1.8 MPa and 45 STP mL/min feed flow rate. Characterization of the supports, calcined fresh and used catalysts were studied by Raman spectroscopy, BET, XRD, TEM, TPR and H-2 chemisorption techniques. XRD confirmed formation of cobalt oxides on the used catalysts. According to the TEM and H-2 chemisorption tests, 480 h continuous FT synthesis increased the average cobalt particle size from about 6 to 6.8nm for Co/GNS catalyst and from about 7.5 to 9.5 nm for Co/CNT catalyst. The initial CO conversion of the Co/GNS catalyst was 12% higher than that of the Co/CNT. For the Co/GNS, 480 h continuous FT synthesis decreased the CO conversion by 3.9%, whereas, under the same reaction conditions the CO conversion for Co/CNT decreased by 20.7%. Regeneration of the Co/GNS and Co/CNT recovered 99.3 and 92.8% of the initial activities of the catalysts, respectively. Significant stability of Co/GNS catalyst in FT synthesis, introduces graphene as an excellent support for the cobalt catalysts. (C) 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.