A man was arrested in Soweto on Tuesday for allegedly raping a 12-year-old mentally handicapped boy, police said.

The child was raped on May 15 when he was apparently lured to the man's backyard room in Zola with the promise of R7, police spokesman Kay Makhubela said.

"The boy was walking to the Philip Kushlik Special School near Baragwaneth Hospital and was near Zola Clinic when the man stopped him and said he could help him get to school," said Makhubela.

Philip Kushlik Special School is for children with cerebral palsy and epilepsy.

The boy, who lives in Snake Park with his parents, accompanied the 43-year-old man who took him to the backyard room where he was raped. The man then gave him R7.

Makhubela said the boy's parents took him to the police station when he told them what happened to him.

The alleged rapist disappeared but eventually returned to his room where Jabulani police arrested him at 3am on Tuesday.

The man will appear in the Protea Magistrate's Court in Soweto on Wednesday.