Pope Francis has paid a heartfelt tribute to his predecessor Benedict the 16th saying his faith and teaching had "enriched and invigorated" the Catholic Church.
He made the comments during an audience with the cardinals who elected him.
The 76 year-old tripped and stumbled, at one point, but quickly recovered.
Francis has said he wants to visit Benedict - but no date has been set.
Addressing the cardinals, he said: "I think with great affection and deep gratitude of my venerable predecessor, Benedict XVI, who during these years of his pontificate has enriched and strengthened the Church with his teaching, his goodness, his guidance, his faith, his humility, and his gentleness, which will remain a spiritual heritage for all.
"As Pope Benedict XVI reminded us so often in his teachings and most recently with his brave and humble gesture, Christ is the one who guides the Church through His Spirit.
"The Holy Spirit is the soul of the Church, with his life-giving force that unifies one body from many: the mystical Body of Christ."
On finishing his address, the Pope greeted, one by one, all the cardinals present in the Clementine Hall personally.
Meanwhile, the Vatican denies that Pope Francis failed to speak out against human rights abuses during military rule in his native Argentina.
Vatican spokesman Fr. Federico Lombardi, said: "The charges refer to the time before Jorge Mario Bergoglio became bishop [of Buenos Aires], when he was Provincial Superior of the Jesuits in Argentina and accuse him of not having protected two priests who were kidnapped.
"This was never a concrete or credible accusation in his regard. He was questioned by an Argentinian court as someone aware of the situation but never as a defendant. He has, in documented form, denied any accusations.
"Instead, there have been many declarations demonstrating how much Bergoglio did to protect many persons at the time of the military dictatorship.
"Bergoglio's role, once he became bishop, in promoting a request for forgiveness of the Church in Argentina for not having done enough at the time of the dictatorship is also well-known."
"The accusations pertain to a use of historical-sociological analysis of the dictatorship period made years ago by anticlerical elements to attack the Church. They must be firmly rejected."
And the Queen is to represented by her cousin the Duke of Gloucester at Pope Francis's inaugural mass.
The Queen, head of the Church of England, has never attended the event but is usually represented.
Pope Francis is officially installed as new leader of the Roman Catholic Church on Tuesday.