A series of ternary hydrotalcites in the nitrate form was prepared with a modified-urea method to obtain active Co-based catalysts for the Fischer-Tropsch synthesis. An optimization study concerning the amount of cobalt in the catalysts (range 5-35 wt%.) and the reaction temperature (220-260 degrees C) is reported. All the samples were characterized by several methods, including XRPD, ICP-OES, SEM, TEM, FT-IR, BET, TPR and TG and tested in a fixed bed reactor. The results suggest the possibility of using synthetic hydrotalcites as Co-based catalysts for the Fischer-Tropsch synthesis. (C) 2013 Elsevier Ltd. All rights reserved.