Frank Murray, one of the commissioners who worked to establish the burial of the Disappeared, was an exceptional public servant, the Taoiseach has said.
Leo Varadkar was leading the tributes to Mr Murray, who died suddenly on Saturday.
He said: "Frank Murray was an exceptional public servant. He enjoyed a long and distinguished career in the Civil Service and I want to acknowledge his many years of loyal service to many governments.
"In particular, I also want to acknowledge the professionalism and sensitivity he brought to his work over the past number of years at the Independent Commission.
Mr Murray was in his late 70s and had been co-commissioner of the Independent Commission for the Location of Victims' Remains (ICLVR) for more than a decade.
Irish Justice Minister Charlie Flanagan described him as a good friend and gentleman.
"I want to offer my most sincere sympathies to his wife Maureen and to his children and grandchildren at this difficult time."
The ICVLR was set up to find the remains of people abducted, murdered and secretly buried by republicans during the Troubles.
The remains of three victims have yet to be found.
Mr Murray began his career with the Irish Civil Service in 1960 and was appointed as secretary general to the Government in 1993 - holding the key position during the crucial period which led to the signing of the 1998 Good Friday Agreement that ended decades of sectarian violence in Northern Ireland.
After his retirement in 2000 he held a number of board level positions with the Public Appointments Service, the Military Heritage of Ireland Trust, the Parnell Society and the Institute of Public Affairs (IPA).
He was appointed co-Commissioner of the ICVLR alongisde Sir Ken Bloomfield in 2006.
Mr Flanagan added: "He had a particular commitment to the cause of the disappeared and their families and he never wavered in his pursuit of the humanitarian objectives of the Commission."
Last week Mr Murray attended a special service for the relatives of the Disappeared in St Patrick's Cathedral, Armagh.
Sir Ken Bloomfield said Ireland had lost a "great man".
He said: "With the sad death of Frank Murray, Ireland has lost a great man in terms of public service and sheer public decency.
"It has been my privilege in recent years to work alongside Frank as a Commissioner for the ICVLR.
"It has been a privilege to know and work with him.
"He will be greatly missed by all who benefited from his wisdom and unalloyed decency."
Families of those who have disappeared have expressed shock and sadness at Mr Murray's death.
Sandra Peake from the Wave Trauma Centre which works to support the relatives said: "His calm compassion and quiet determination to see it through even or perhaps especially when a search had been unsuccessful gave the families comfort and reassurance that they would not be abandoned.
"He will be missed and will not be forgotten.
"The condolences of the families of the Disappeared go to Frank's wife and family."
- Press Association and Digital Desk