The royal commission into child sexual abuse will today examine cases of abuse that took place at four Salvation Army boys' homes in Queensland and New South Wales.

The two-week investigation will scrutinise how the prominent charity has dealt with instances of child sexual abuse, and how the Salvation Army dealt with offenders in its ranks.

The Salvation Army says the abuse, most of which took part in the 1960s and 70s, is a "failure of the greatest magnitude".

Robert Conway was 13 when he was sent to one of the boys' homes.

"First impressions... well I was molested the first night I was there by the major who ran the place," he said

He says the boys also suffered routine severe physical abuse which he believes the royal commission should also be examining.

Lewis Blayse was among the children at the Alkira Salvation Army Home in Queensland.

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"What I would say to people is, they have been very shocked about what they have heard in the past from the other churches," he said.

"What they are going to hear from the Salvation Army one, is going to be much, much worse, because it was unique in that it was always associated with extreme violence and that is the part that will be the new shock."

Salvation Army Commissioner James Condon says it is a dark part of the organisation's past and needs to be brought out into the open.

"I've read through records. I've read through reports and it just for me magnifies the incredible regret that I feel," he said.

"My heart is aggrieved by what happened while people were supposedly in the care of the Salvation Army."

Salvation Army 'accepts responsibility' for abuse

In 2010, the Salvation Army made a formal apology for the abuse of children in its care up to the 1990s.

Mr Condon says he accepts responsibility for what happened.

"I go with a heavy heart because I do deeply regret that these things happened to former residents who were supposed to be in our care," he said.

"We accept responsibility for what happened and we, being the leaders of the Salvation Army for today, certainly accept responsibility, we take that upon ourselves."

Royal commission chief executive officer Janette Dines says many of the cases were not reported until the 90s.

She says many victims did not report abuse for decades because they were too scared.

"The striking thing about this next public sitting is the severity of the physical and the sexual abuse and the psychological trauma and the threat and the fear of punishment that the children lived under if they did disclose the abuse," she said.

Ms Dines says the hearing will look at how the Salvation Army responded to the cases.

"What sort of processes did the Salvation Army have in place to respond to complaints of child sexual abuse?" she said.

"What sort of processes were there to prevent perpetrators moving from homes? What sort of disciplinary processes were there?

Today's public hearing in Sydney is the fifth session being heard by the Royal Commission into Institutional Responses to Child Sexual Abuse.