Activity and selectivity of H-2, CO, syngas pretreated and non-pretreated Ruhrchemie catalyst (100 Fe/5 Cu/4.2 K/25 SiO2 on mass basis) used for the Fischer-Tropsch synthesis (FTS) were studied in a stirred tank slurry reactor (STSR). Catalyst activity was the highest after the CO and H-2 pretreatments, whereas the non-pretreated catalyst was the least active. Methane selectivities on the CO, syngas reduced and unreduced catalysts were similar (3.9-4.3 wt.%), and lower than that on the H-2 reduced catalyst (5.3%). Liquid plus wax (C-5(+) hydrocarbons) selectivity was high in all four tests (similar to80%). The H-2 reduced catalyst produced less olefins and had the highest 2-olefin selectivity, whereas the non-pretreated and CO pretreated catalysts had the highest olefin content and the lowest 2-olefin selectivity. Attrition strength of the Ruhrchemie catalyst after 429 h of FTS was found to be adequate under severe hydrodynamic conditions encountered in the STSR. Reduction in the volume moment diameter was 14.3%, whereas, increase in fraction of particles smaller than 10 mum was only 2.6%. (C) 2004 Elsevier B.V. All rights reserved.