A royal commission decision to hear from retired Catholic bishop Geoffrey Robinson has been welcomed by a key organisation representing survivors of abuse in institutions.

Author and theologian Bishop Robinson, who will give evidence on Monday at a public hearing of the child sex abuse royal commission, is described as a "voice in the wilderness" within the church by Care Leavers Australasia Network (CLAN).

CLAN - which has 1000 members, the oldest aged 90 - is a support, advocacy, research and training network for people who grew up in Australian orphanages, children's homes, foster care and other institutions.

The network's executive officer, Leonie Sheedy, said Bishop Robinson has actively supported the rights of care leavers and abuse survivors for many years.

Ms Sheedy said the bishop was supportive of the network in its earliest days and "is one of just a handful of Australian Catholic leaders who have displayed courage through their outspoken support and many acts of kindness towards ... survivors of church sex abuse".

Despite ailing health, Bishop Robinson will appear at the royal commission to speak about the history and development of the Catholic Church's response to child sexual abuse before the introduction of its own process, Towards Healing.

He will also give evidence on his membership of the College of Consultors of the Archdiocese of Sydney and the operation of Encompass Australasia, a program for clergy with psychosexual disorders, and his own discussions with senior Vatican officials.