The activity and selectivity of rhenium promoted cobalt Fischer–Tropsch catalysts supported on Al 2 O 3 , TiO 2 and SiO 2 have been studied in a fixed-bed reactor at 483K and 20bar. Exposure of the catalysts to water added to the feed deactivates the Al 2 O 3 supported catalyst, while the activity of the TiO 2 and SiO 2 supported catalysts increased. However, at high concentrations of water both the SiO 2 and TiO 2 supported catalyst deactivated. Common for all catalysts was an increase in C 5+ selectivity and a decrease in the CH 4 selectivity by increasing the water partial pressure. The catalysts have been characterized by scanning transmission electron microscope (STEM), BET, H 2 chemisorption and X-ray diffraction (XRD).