Aaron David Vincent, 28, pleaded guilty in Port Kembla Local Court last year to one count of having sex with a child aged 14 to 16 years, stemming from a sexual encounter he had with a 15-year-old girl in March 2014.

During sentencing procedures in Sutherland District Court on Wednesday, the court heard Vincent and the girl had agreed to "hang out" during the weekend of March 24 and at one point went to his Victoria Street unit.

They began kissing and had consensual sex.

The following day, Vincent detailed the sexual encounter to a Lifeline counsellor via an internet chat forum, and the matter was referred to police.

Although the victim initially refused to assist with the investigation, she eventually provided a statement to police at the end of April, leading to Vincent's arrest.

Vincent pleaded guilty in Port Kembla Local Court last November to a charge of under-age sex.

The court also heard Vincent had been placed on the child protection register after he was caught with child pornography in South Australia in 2011.

In sentencing Vincent on Wednesday, Judge Paul Conlon said the offending was at the lower end of the scale and he had shown contrition for his actions.

"The way in which he has disclosed his offending conduct is an indication of the guilt he felt for his conduct," he told the court.

He was sentenced to a non-parole period of 10 months and with time served will be eligible for release on February 28. Judge Conlon imposed an additional five-month supervised parole period.