The man was arrested in Lurgan on suspicion of membership of a prescribed organisation and possession of information likely to be of use to terrorism.
He has been taken to Musgrave Serious Crime Suite for questioning. A number of mobile phones, electronic tablets and a memory stick were also seized.
Speaking about the arrest, Detective Inspector Adrian Brown said: “As part of our investigations into ongoing dissident republican activity we have arrested a man earlier today.
“We will continue to disrupt the activities of those who wish to terrorise the community with their twisted ideologies so that people can live without fear.”