A Bloxwich youth was attacked by three masked robbers as he walked along a canal towpath earlier this month.
The 17-year-old was confronted and threatened by the men near to Hildicks Bridge off Goscote Lane between 8pm and 8.30pm on Monday 7 January.
They demanded he hand over his mobile phone, which he did, and they then ran off towards the road.
Detective Constable Jon Baker, of Walsall CID, said:
“Fortunately the victim was not injured but was left very shaken up following the robbery.
“We want to hear from anyone who may have witnessed the incident or who saw three masked men in the area on the evening.
“If you have any information which could help our investigation, no matter how insignificant you think it may be, please contact us.”
Anyone with information about the robbery should call police on 101 or the independent charity Crimestoppers anonymously on 0800 555 111.