The requiem mass will be celebrated on Friday by Cardinal Joseph Ratzinger, head of the Vatican Congregation for the Doctrine of the Faith, the Vatican said on Monday.
The 77-year-old Ratzinger, a German who was very close to the Pope, is one of the most powerful figures in the Vatican government and considered among possible successors.
The body of the Pope, who died on Saturday ending a historic but sometimes divisive papacy spanning 26 years, will be taken to St Peter's Basilica later on Monday, the day for public viewing.
Some young pilgrims, eager to be the first to see the Pope's body, staked out positions in cobblestoned St Peter's Square.
Clad in crimson
"If it hadn't been for this Pope, I would have completely lost my faith. I always trusted him, and needed to come here today to see him," said 22-year-old Silvia Mazzacani, who took an overnight train from northern Italy.
The body of the Pope was put on
view to the world by Vatican TV
The Pope's corpse, clad in crimson and white vestments, was put on view for the world by Vatican television on Sunday. His face clearly showed signs of the physical suffering that wracked him in the final days of his life.
News of his death brought the red-hatted princes of the Church rushing to Rome, their minds turning to the conclave set for later this month that will elect a new man to run the 1.1 billion-member Church.
US Cardinal Theodore McCarrick called the looming vote an
At their first meeting on Monday, the cardinals are to decide the funeral rites and swear an oath to maintain strict secrecy about "all matters in any way related to the election of the Roman pontiff".
Up to 200,000 worshippers gathered in St Peter's Square on Sunday to hear the Pope's own words read out at a Requiem Mass for the world's best known religious leader, who helped topple communism and stamped a rigid orthodoxy on his Church.
"If it hadn't been for this Pope, I would have completely lost my faith"
Silvia Mazzacani, 22-year-old Italian
"It is love which converts hearts and gives peace," the text, which was read out by an archbishop, said.
Aljazeera's correspondent in Rome, Imad al-Atrash, said the Italian government has deployed more than 10,000 policemen to secure safety in the city. More than two million visitors are expected to arrive on Monday to bid farewell to the deceased Pope, he added.
There is a strong sense that the successor should be Italian, in keeping with a 450-year-old traditions with only occasional exceptions, al-Atrash said.