Australians who were raped and molested by priests are hoping to learn the truth about what a top Vatican cardinal knew about their attackers when he testifies before an investigative commission at a Rome hotel.

Thanks to a crowd-funding campaign, about two dozen Australian sex abuse survivors and their companions travelled across the planet to be on hand when Cardinal George Pell testifies Sunday night via video link before Australia's Royal Commission.

David Ridsdale, who was abused for four years in Ballarat in Australia's Victoria state, said the city has been devastated by the huge numbers of abuse victims, scores of whom have committed suicide. He said Ballarat wants Pell to "stand up and take responsibility on behalf of the church" for what transpired in his hometown.