A woman who was walking to work was robbed of cash and bank cards in a Wellingborough alleyway at about 7.10am on Friday (August 24).
The victim was walking in the direction of Tesco and as she walked down an alleyway adjacent to the Tesco store service road in Whitworth Way, she was approached by a man who threatened her, forcing her to hand over the items.
A police spokesman said the victim ran away after the robbery.
The offender is described as 6ft, aged 40 and with an average build.
His hair and face were covered, with only the eyes visible.
He wore a black and grey tracksuit.
Anyone with information about the robbery can contact Northamptonshire Police on 101 or Crimestoppers anonymously on 0800 555111.