Gavin Parry ran out of the room at his grandmother's home in tears to seek a hiding place. His family, of Blaenavon, near Pontypool in Gwent, assumed he had gone outside in a bad temper.
When there was no sign of him they started searching the house and eventually found Gavin hanging in a cupboard.
He had tied the belt from his grandmother's raincoat around his neck.
Neighbours and paramedics battled to revive him but Gavin was pronounced dead on arrival at hospital. He had been spending the evening with his mother, aunt and grandmother.
His mother, Tracey Parry, 33, a mature student, said: "Gavin was messing around with his aunt as they often did.
"He said something about wanting some pocket money and Jodie [his aunt] just gave him a little smack on the bottom. Gavin ran out of the room and we heard a door slamming. We thought he had run out of the house. I can't believe that he was in the cupboard just a few feet away from the living room.
"He was the sort of boy who liked to be the centre of attention. He played pranks, like hiding in the boot of my car or jumping out of the windows of the house.
"He was a happy little boy and would do anything for me."
Gavin was the eldest of three children - brother of Nathan, seven, and Ieuan, two.
Gavin's parents were not married. His father, Keith Jenkins, 37, said: "He was a bubbly boy who always had a smile on his face. He could be a bit mischievous and was always messing about, but I can't believe something like this has happened."
A Gwent Police spokesman said: "It is a terrible waste of a young life. We don't know what was going through this lad's mind at the time. A post- mortem examination was held yesterday and an inquest will be opened later this week."
Insp Tony Wilcox, of Gwent police, added: "With a child that age we can only assume it was misadventure. There was some sort of chastisement, but we don't know whether that was linked to the tragedy."