A masked robber attacked a shopkeeper with a hammer before stealing cash and cigarettes during a raid at a shop in Desborough.
The robbery took place at the Cost Cutters store in Broadlands between 8.45pm and 9pm on Tuesday (November 26).
A man entered the shop and threatened the shopkeeper with hammer, demanding they open the till.
The offender hit the victim on the arm with the hammer, causing minor injuries.
The offender is described as white, about 5ft 5in, of medium build and in his late teens to mid 20s.
He was wearing black trousers, a black and silver jacket, black gloves, a cap and had masked his face using a scarf.
Witnesses, or anyone with information, should phone Northamptonshire Police on 101. Alternatively, information can be given anonymously to Crimestoppers on 0800 555111.