Facebook Messenger has been used to try to deradicalize extremists in a pilot project funded entirely by the company, wrote BBC.
People posting extreme far-right and Islamist content in the UK were identified and contacted in an attempt to challenge their views.
Of the 569 people contacted, 76 had a conversation of five or more messages and eight showed signs it had a positive impact, researchers claim.
Privacy campaigners say it means Facebook is straying into surveillance.
Technology companies have been urged to do more to stop extremist material littering their sites following a series of cases involving people who were radicalized online.
This pilot was led by the counter-extremism organisation Institute for Strategic Dialogue (ISD), which says it was trying to mimic extremists' own recruitment methods.