Thomas Marshall was last seen by his mother near his home on Waveney Road, Hull, on his way to school around 8am.
His family were informed by his school that he never arrived there and he hasn't been seen since.
He is known to frequent parts of east Hull. He could be with an older teenager.
Thomas is white, 4ft 11ins with mousey coloured hair. He was wearing a grey Nike top, black trousers, black spotty Nike trainers and carrying a blue school bag.
Anyone who sees him is asked to call 101, quoting log 463 of May 10.