The locations include 15 state-run children's homes, 13 institutions run by the Catholic Church, four borstals or training schools, and three institutions run by Protestant churches or voluntary sector organisations.
The announcement came on Thursday, as the chairman of the inquiry Sir Anthony Hart launched a campaign to encourage survivors to contribute to the review of alleged mistreatment and abuse in residential institutions over a period of 75 years.
Advertising will feature on 80 bus shelters throughout Northern Ireland and Outreach posters and literature will be distributed to promote the call.
More than 170 state and church run facilities that operated from 1922 to 1995 have been identified by the inquiry to date.
The institutions at the centre of the initial review have been named by victims who have been in touch with the inquiry. Sir Anthony said they would not be named publicly at this stage.
The majority of the 15 state-owned homes were run by local authorities.
The review is expected to take three years to complete and will cost £15-19m.
We have to do our work thoroughly and we are not going to skimp on what we do, but it also means that we are not going to go on for years and years and years.
Sir Anthony Hart, inquiry chairman
A total of 175 people have applied to take part in the inquiry so far - 90 have already gone through the acknowledgement forum process. A quarter of those who applied live outside Northern Ireland.
Victims who have come forward with claims of childhood abuse already range from being in their 30s to some now in their 80s. Four out of every five interviewed have signalled a willingness to go before an inquiry hearing.
An acknowledgement forum panel will eventually produce a report to the inquiry chair detailing the various experiences recounted to them in a fully anonymised form.
Sir Anthony said that further institutions could still come under investigation as more evidence is gathered.
"This is their opportunity to tell society through the inquiry how they were treated in these institutions and, if they were ill-treated, we will have to investigate that and we will investigate it," he explained.
"So for them it is their opportunity, almost certainly for the first time, to say what happened to them."
However, Margaret McGuckin from Survivors and Victims of Institutional Abuse (SAVIA) said she has concerns over when the process will come to a conclusion and the lack of resources in place to help survivors.
She said this week's state apology from Taoiseach Enda Kenny for the Magdalene laundries was a reminder of the redress that survivors in Northern Ireland are still seeking.
"The government in the Republic held an inquiry, then they set up a redress and funding scheme, and then they apologised. And they meant that apology," she said.
"That apology meant so much and many of our people were in tears when they phoned me and said: 'When will our day come?'"
We need an apology, we need to be compensated, we need to be redressed because we do not want to live with this every day of our lives.
Margaret McGuckin, Survivors and Victims of Institutional Abuse
Ms McGuckin said that a compensation fund needs to be implemented for victims of institutional abuse.
"I have been touch with the religious orders yesterday, who are waiting on the government to contact them," she said.
"They want to get this over with themselves and I don't what's holding back our government."
Alison Diver has taken part in the acknowledgment forum. She was abused while at Nazareth House in Londonderry.
She recognised the importance of the inquiry, but said she was distressed by the lack of aftercare.
She told UTV: "It's a must. I think even before you go, to take on board what you are doing and the way it could affect you afterwards."
Another victim, who does not want to be named, was abused in a Catholic reform school when he was 15 by a member of the Christian Brothers.
He said the inquiry means closure for him and others.
But he added that he wanted to see police arresting those involved in alleged abuse.
"It means acceptance within myself to say, ok, that happened to me, but I have to move on with my life," he said.
"I don't think the inquiry is going to give us all the answers that we need - no inquiry can do that.
Historical Institutional Abuse Inquiry telephone: 0800 068 4935
"But what this inquiry, I hope, can do is for the likes of myself and others is that we can go away and say: 'Well we got something, we got answers, we got treated as human beings.'"