Abstract: A process for producing an indoline of the formula: ##STR1## wherein R.sub.1 is a hydrogen atom, a lower alkyl group, a lower alkoxy group, a nitro group or a hydroxyl group, R.sub.2 is a hydrogen atom, a lower alkoxy group or a nitro group, and R.sub.3 is a hydrogen atom, a lower alkyl group or a substituted lower alkyl group, by a cyclization reaction of a 2-halogenophenethylamine of the formula: ##STR2## wherein R.sub.1, R.sub.2 and R.sub.3 are as defined above, and X is a halogen atom, in the presence of a copper type catalyst and a dehydrohalogenating agent, characterized in that copper bis(8-hydroxyquinolinolate) is used as the copper type catalyst, and an alkali is used as the dehydrohalogenating agent.