A Kettering pensioner asked a group of teenagers to leave him alone after they kept kicking his door - only for one to punch him.
The victim, 72, had his front door to the shops in St John's Road repeatedly kicked and asked them to leave his home alone after following them.
But as he turned to walk away, between 7.30pm and 8pm on December 11, one of the group punched him to the ear leaving him shaken and sore.
A police spokesman said: "The suspects are described as a group of boys and girls aged 14 to 15.
"The boy who assaulted the man is described as white, of slim build and average height, with black-framed glasses.
"Anyone who saw the incident, or who has information about it, is asked to call Northamptonshire Police on 101."