Abstract: A two step process for the obtainment of white oils, using hydrocarbons which are heavy alkylates obtained as a by product in the manufacture of detergent range linear alkylbenzene (9-15 carbon atom paraffin chains) as the raw material is described.The first step consists of pretreatment (of an absorbent nature) of the feed, with an activated magnesium silicate in order to eliminate the heaviest components. In a second stage, the resulting treated product acts as a feed in a hydrogenation process to produce white oils, in a presence of a hydrogenation catalyst formed by a metallic component of the group of iron and/or nickel upon a refractory inorganic oxide support.The catalytic hydrogenation process is carried out in a fix bed reactor with down flow.It is useful in the pharmaceutical and food industries.