Abstract: There is provided a process for recovering boron trifluoride catalyst from an oligomerization mixture, which comprises introducing an oligomerization mixture containing catalyst comprising boron trifluoride and a complex of boron trifluoride and cocatalyst into a copper-nickel-made recovery reactor, heating the oligomerization mixture at or above a decomposition temperature of the complex, and separating and recovering boron trifluoride from the oligomerization mixture. According to the process, the boron trifluoride can be recovered effectively from the oligomerization mixture without causing the corrosion problem of the recovery reactor.