Abstract: A process for hydrogenating long chain hydrocarbons includes continuously feeding a feedstock having long chain hydrocarbons into a slurry bed including a slurry of catalyst particles in a slurrying liquid. The slurry bed is contained in a reaction zone and the feedstock enters the reaction zone at a low level. A hydrogenation component is fed continuously into the slurry bed, at a low level. The hydrogenation component is allowed to react with the feedstock, to hydrogenate the feedstock, as the feedstock and hydrogenation component pass upwardly through the bed. Hydrogenated long chain hydrocarbons are withdrawn from the reaction zone at a high level, as a hydrogenation product. Any excess hydrogenation component is withdrawn from the reaction zone at a high level.