The invention concerns a process and apparatus for treating a feed comprising ethylenic and acetylenic compounds. In the process of the invention, the feed is sent to a distillation step, a C4 cut and a C5+ cut are recovered, a drawn fraction comprising acetylenic compounds is treated in at least one hydrogenation step, and an effluent which is depleted in acetylenic compounds is recycled. The distillation step comprises: an initial step for pre-fractionating the feed, carried out in a pre-fractionation zone included in a distillation column; and at least one complementary fractionation step, carried out in a zone which comprises a portion A, which is distinct from and not adjacent to the portion B of the pre-fractionation zone below the supply, in which the fraction drawn from a point in A is recovered with a C4/C5+ ratio that is higher than that of the feed.