The boy, who has not been named yet, was last seen leaving Newquay's sports centre on his own at around 3pm. He was wearing a red Manchester United tracksuit top, football socks and white football boots.
Police have declared the incident high risk due to the boy's age and are appealing for information.
Anyone with information is asked to call 999 and to quote crime reference 04/16/03.
More top news
Slippy start tomorrow with frost & ice
The court will determine how much the UK government and travel firms knew about the risk of an attack on tourists holidaying in the area.
Car insurance for young people could rise by £1,000 a year after a change to compensation payouts for those with life-threatening injuries.