A series of catalysts, Fe:Co/TiO2, were made with different total metal loadings (Fe:Co wt.% loading; 1: 1-5:5), with different Fe:Co ratios (at 10% metal loading) and using different synthetic procedures (impregnation versus physical mixing). The catalysts were characterised by BET, CO-chemisorption and Mossbauer spectroscopy. Their Fischer-Tropsch (FT) activity/selectivity properties were also measured. The co-impregnated catalysts revealed that the 5:5 Fe:Co catalyst showed higher activity than catalysts prepared with either 2.5:7:5 or 7.5:2.5 Fe:Co ratios. Physically mixed samples of Fe/TiO2 and Co/TiO2 showed different selectivities and also gave better FT activity than equivalent co-impregnated Fe:Co samples. The reducibility behaviour and Mossbauer spectra of the Fe:Co samples suggested that the catalyst activity and selectivity changes related to the Co phase, Fe-Co alloy formation and the ability of the Co to enhance the reducibility of the Fe. A relationship between reduction level and activity was observed. The bimetallic systems also showed good stability and only modest changes in selectivity with time on line. (c) 2005 Elsevier B.V. All rights reserved.