On October 16 1998, the Norwegian Nobel Committee said it had decided to award the Nobel Peace Prize to the two men "for their efforts to find a peaceful solution to the conflict in Northern Ireland".
In its explanation of the decision to select Mr Hume as one of the joint winners, the committee described him as being ''the clearest and most consistent of Northern Ireland's political leaders in his work for a peaceful solution".
The committee also said: "The foundations of the peace agreement signed on Good Friday 1998 reflect principles which he has stood for".
His political counterpart, now Lord Trimble, was honoured for having demonstrated ''great political courage when, at a critical stage in the process, he advocated solutions which led to the peace agreement".
It was a clear reference to his decision to sign up to the Good Friday Agreement in April of that year and his work in bringing a majority of Unionist opinion to support the accord.
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Speaking ahead of tomorrow's anniversary, SDLP deputy leader Nichola Mallon said: "The SDLP are extremely proud of John's pivotal role in the peace process and we will never stop striving to carry on the work of creating an Ireland of equals that John envisioned".
"As we mark 20 years since John Hume and David Trimble were jointly awarded the Nobel Peace Prize on that monumental autumn day in Oslo 1998, we are reminded that in the face of grave challenges- partnership, co-operation and a desire to work for the common good is entirely possible," she said.
"Following on from his poignant words from that day, the SDLP will continue to find the courage to resolve the situation we face in these politically uncertain days so that our children too can look to the future with a smile of hope."
Mr Hume, who was SDLP leader at the time, was at his home in Derry when he received word of the prize.
He described the accolade as ''an expression of the total endorsement of the work of very many people''.
"This isn't just an award to David Trimble and myself," he said.
"It is an award to all the people in Northern Ireland."
Lord Trimble, Stormont first minister from 1998 to 2002, said it was "a great honour but it's not for me personally".
"I think people should not look at it like that," he said.
"What was done in terms of achieving an agreement was done by a tremendous amount of people. I'm thinking of my colleagues in the party who have worked so hard and of the people of Northern Ireland as a whole who have longed for peace to come.
"And I hope very much that this award does not turn out to be premature because there is still work to be done to secure peace in Northern Ireland."
The accolade was later bestowed on the two men during a ceremony in Oslo in December 1998.