The present invention relates to a method for preparing linear alpha-olefins (LAO) by oligomerization of ethylene in the presence of solvent and homogenous catalyst, comprising the steps of: (i) feeding ethylene, solvent and catalyst into an oligomerization reactor, (ii) oligomerizing the ethylene in the reactor, (iii) removing a reactor outlet stream comprising solvent, linear alpha-olefins, ethylene, and catalyst from the reactor via a reactor outlet piping system, (iv) transferring the reactor outlet stream to a catalyst deactivation and removal step, and (v) deactivating and removing the catalyst from the reactor outlet stream, characterized in that at least one organic amine is added into the oligomerization reactor and/or into the reactor outlet piping system.