Low pressure Fischer-Tropsch synthesis was tested using iron catalysts reduced by three different reducing gases. In this regards, three reactors were set up in parallel and each of them loaded with the same quantity of the iron catalyst (FeCuKSiO2). After loading, the catalysis in the first reactor was reduced with synthesis gas (a combination of carbon monoxide and hydrogen). The catalyst in the second reactor was reduced using hydrogen (H-2) gas, and while that in the third reactor was reduced with carbon monoxide (CO) gas. In this study only the gas-phase products leaving the reactors were analysed and compared under the same operating conditions such as flow rate, pressure and temperature for 1000 h TOS. The results obtained indicate that the initial use of different reducing agents does not have a large impact on the long term catalyst activity but does have an impact on long term selectivity. The three reactors stabilize to about the same overall CO conversion of 14.5% which corresponds to a consumption rate of 2.64 x 10(-4) mol/min.gcat (reactivity) after about 150 h while the selectivities in the three reactors are not the same. Methane selectivity showed the trend: Carbon monoxide reduced > Syngas reduced > Hydrogen reduced. Furthermore, reducing with CO gives much more olefins than reducing with syngas and H-2. The paraffin production rates did not follow a consistent trend. (C) 2017 Elsevier B.V. All rights reserved.