Police have charged a 49-year-old man who investigators allege gave a teenage girl money and drugs for sex.

Investigators say Jason Scott, from Kellyville Ridge, sexually assaulted his 15-year-old victim in hotel rooms in Parramatta last October and in Killara last November.

The pair met through a friend of the girl and Mr Scott offered her ice and money in exchange for sex on both occasions, police allege.

It is understood the girl contacted police, and investigators from the State Crime Command's Child Abuse Squad began an investigation.

Mr Scott was arrested at his home on Tuesday morning and charged with two counts of sexual intercourse with a girl between the ages of 14 and 16 and two counts of causing a child between the ages of 14 and 18 to do an act of child prostitution.

He was taken to Castle Hill police station, then faced Parramatta Local Court where he was granted conditional bail ahead of his next appearance in the same court on August 22.