Co@Ru/gamma-Al2O3 core-shell structure catalysts with Co/Ru different weight ratios are successfully prepared via surface displacement reaction. This novel route including reduction of Co core by NaBH4 on the surface of gamma-Al2O3 and then substitution of Co species with Ru species, the resultant of reduction of RuCl3 precursor with N2H4. These catalysts are characterized with techniques X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), high resolution transmission electron microscopy (HRTEM), N-2 adsorption/desorption (BET), temperature programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS) and Fourier transform infra-red (FTIR) of CO adsorbed. The characterization results confirm a uniform dispersion of Co@Ru nanoparticles with core shell structure over gamma-Al2O3. The core-shell Co@Ru/gamma-Al2O3 catalysts show the remarkable catalytic activity towards Fischer-Tropsch synthesis (FTS) in comparison with Co/gamma-Al2O3, which is related to special core shell structure. These catalysts exhibited excellent abilities in the cases of increasing formation of long-chain hydrocarbons and suppressing selectivity to lighter hydrocarbons. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.