Catholic cardinals will start their conclave to elect a successor to Pope Benedict on the afternoon of Tuesday 12 March.
The vote follows Pope Benedict XIV's surprise abdication last month after nearly eight years in office.
Most of the world's cardinals are already at the Vatican where they have held closed-door discussions on the problems facing Church and to decide on the profile of the man they want to lead them.
The prelates decided on Friday to begin their secret ballot in the frescoed Sistine Chapel on Tuesday afternoon following a Mass in St Peter's Basilica in the morning.
A total of 115 cardinals are expected to take part in the elaborate ritual, which continues until one of them receives a two-thirds majority.
There is no clear favourite to take the helm of the Church, which faces an array of problems, from sexual abuse scandals to internal strife at the heart of the Vatican administration, Reuters reports.
The cardinals are likely to hold just one ballot on the first day and up to four ballots each day thereafter.
Benedict was elected in barely 24 hours in 2005. His predecessor, John Paul II, became pope after eight rounds of voting spread over three days in the 1978 conclave.
The cardinals have made clear they want another quick conclave this time to make sure they can all return to their dioceses in time to lead Easter celebrations - the most important event in the Roman Catholic calendar.
Cardinals were in the past locked into areas around the Sistine Chapel, famed for its Michelangelo frescoes, and not allowed out until they had chosen a new pontiff.
But the rules changed before the 2005 conclave and the prelates now get to reside in a comfortable Vatican hotel while they are not voting in the chapel itself.
Jamming devices will also be installed around the Sistine Chapel and the hotel to stop outsiders eavesdropping and to prevent mobile phone usage in the area.