The present invention relates to a method for catalytic deoxygenation of process fluids of olefin dimerization processes. According to the invention at least one process fluid containing oxygenates is brought into contact with a deoxygenation catalyst at, at least one location in a column or connected to a column. The present invention relates also to a process for dimerization of olefins, wherein at least part of olefin feed is dimerized in at least one dimerization reaction zone to produce a first product stream comprising oxygenates, and separating in a distillation zone, comprising one or more distillation columns, the first product stream into a second product stream and a third product stream and at, at least one location of the distillation column or a vessel connected to the distillation column is located a deoxygenation catalyst for decomposing oxygenates.