CO2-hydrogenation presents a promising pathway for the synthesis of renewable drop-in hydrocarbon fuels from waste CO2. This is especially valuable when using “hard-to-mitigate” CO2, e.g. from the cement industry. Iron has been seen as the most promising catalyst for CO2-hydrogenation yielding liquid fuels and is known to exhibit a conversion-selectivity relationship which may be exploited to increase the yield of C2+ hydrocarbons. The original intention was to vary the CO2-conversion in a slurry phase reactor and assess the conversion-selectivity relationship. However, it was noticed that the catalyst performance improved significantly upon operation at sufficiently high conversion. This effect could be replicated by in-situ dosing of water following the catalyst activation during experimentation implying that product water caused the improved performance after exposure at elevated conversion levels.