The effect of Au addition on the structure of Co/Al2O3 and Co/SiO2 systems and their performance in the Fischer-Tropsch synthesis (Fr) reaction has been investigated. In particular, the effect of the addition of Au (0-5%) to 10% Co/Al2O3 and 10% Co/SiO2 catalysts has been evaluated. An improvement in Co reduction was observed by adding Au to the supported Co/Al2O3 and Co/SiO2 catalysts. For both the silica and alumina-supported catalysts the catalyst activity increased significantly after the addition of Au up to 1.5 wt.%. Further increases in Au led to small increases in catalyst activity. The effect of adding Au to the supported Co catalysts was found to be similar to the effect of adding noble metals (Ru, Re and Pt): the Au also improved the catalyst reducibility and activity in the Fr reaction. The most significant effect of Au addition on the catalyst activity was found for 5%Au/10%Co/Al2O3 where the maximum conversion was more than six times higher when compared to the activity of the undoped catalyst (10%Co/Al2O3) (c) 2011 Elsevier B.V. All rights reserved.