A 15-year-old boy was walking along a Northamptonshire street when he was approached from behind.
The two men approached the boy as he was walking along Alfred Street in Kettering with his friend.
Two men then assaulted him and stole his phone.
The robbery happened sometime between 6 and 7pm on Saturday, February 28.
Witnesses, or anyone with information, is asked to call Northamptonshire Police on 101.
Alternatively, they can call the independent charity Crimestoppers anonymously on 0800 555 111 or use the anonymous online form at www.crimestoppers-uk.org.