Interest in mentoring, which is an innovative method in adult education (CEDEFOP, 2013), has been growing rapidly in Europe, especially since the Lisbon European Council in 2000. In Greece, this interest has found expression either through the development of educational material in the context of adult educator training programmes, or the investigation of the mentoring needs of adult learners (Koutsoukos, 2021). In spite of the obvious fact that the mentor plays a key role in ensuring that the mentoring process is constructive and successful, there has been little research to date on the attributes of an effective mentor in adult education. The present study, using multimethod research, examined the perceptions of 337 Greek adult educators as to what characteristics constitute an effective mentor, as well as the role and the selection criteria of a successful mentor. The findings indicated that the key qualities of an effective mentor were: having sufficient training in adult education and mentoring, teaching, communication and relational skills, as well as having a positive attitude to lifelong learning and a willingness to innovate. In addition, the role of an effective mentor was perceived by the study participants as being a trainer, a model teacher, as well as an equal partner.