Abstract: An improvement is described on a process for recovery of butadiene from a C.sub.4 hydrocarbon mixture additionally containing minor amounts of C.sub.5 saturated and unsaturated hydrocarbons, said hydrocarbon mixture being obtained as the overhead product of an initial hydrocarbon fractionation employed to separate larger quantities of C.sub.5 and heavier hydrocarbons from the hydrocarbon mixture, wherein the hydrocarbon mixture is subject to extractive distillation in the presence of a polar solvent e.g. acetonitrile, in which butadiene is separated from the fat solvent bottoms of extractive distillation by sequential low pressure flashing and stripping, followed by compression of the combined vapors of flashing and stripping with part of the compressed vapors being recycled as reboiled vapor to the extractive distillation and the remainder being again stripped at a higher pressure to recover butadiene therefrom. In this improved process, butadiene purification problems associated with carry over of C.sub.