Boys, aged 12 and 13, were robbed at knifepoint on a Rotherham street.
The boys were held up by a man who approached them in St Ann's Road, Eastwood.
They told South Yorkshire Police that the robber, who was around 19, threatened one of them with a knife and demanded that he handed over his phone and money.
The robber was 6ft tall, skinny, spoke with a foreign accent and was wearing grey jogging bottoms with a hooded top.
Anyone with information about the incident on Monday, October 24 should call South Yorkshire Police on 101.