Benedict XVI publicly expressed his joy at the election on 27 January of 62-year-old Metropolitan Kirill of Smolensk and Kaliningrad as the new Patriarch of Moscow and of All Russia. His enthronement took place on Sunday, 1 February.
The Russian Orthodox Church has around 100 million adherents in Russia and several million more around the world.
The new head of the Russian Orthodox Church has often travelled and met priests of Western churches as the long-time head of his Church's foreign relations department.
Among those he met was Cardinal Joseph Ratzinger, now Pope Benedict XVI, and experts suggest a historic meeting of the Russian Patriarch with the Pope could occur.
'A meeting with Benedict XVI is possible like never before,' according to Moscow- based religious expert Maxim Shevchenko, who heads the Centre for Strategic Research into Contemporary Religion and Politics. 'They have known each other for several years and their views on the modern world are very close.'
At a general audience following Patriarch Kirill's election, Benedict said, 'I invoke upon him the light of the Holy Spirit for a generous service to the Russian Orthodox Church, entrusting him to the special protection of the Mother of God.'
In a telegram sent to the newly- elected Patriarch, the Pope wrote: 'May the Almighty bless your efforts to maintain communion among the Orthodox Churches and to seek that fullness of communion which is the goal of Catholic-Orthodox collaboration and dialogue.
'I assure Your Holiness of my spiritual closeness and of the Catholic Church's commitment to co-operate with the Russian Orthodox Church for an ever clearer witness of the truth of the Christian message and to the values which alone can sustain today's world along the way of peace, justice and loving care of the marginalised'.
The Catholic Archbishop in Moscow, Paolo Pezzi, hailed Kirill's election as a hope for the continuation of ecumenical dialogue. He called the election 'very positive news' and said that it promised 'continuity and recognition of the work of the former patriarch, Alexy II.'
The new Patriarch, who received 508 of the 700 votes cast, had functioned as the interim head of the Church following the death of Patriarch Alexy II on 5 December 2008.
The Vatican's Pontifical Council for Promoting Christian Unity noted that Kirill was 'a Patriarch with whom we have maintained fraternal relations for many years, and who met the Holy Father immediately following his election in April 2005, and again in the months of May 2006 and December 2007.
'We trust we will be able to continue together down the path of mutual understanding we have already begun. We do not, of course, wish to lose sight of the difficulties that still remain, but we are ready and willing to co-operate in the social and cultural fields in order to bear witness to Christian values while, nonetheless, not forgetting that the ultimate aim of dialogue is the realisation of the testament of Jesus Christ our Lord: the full communion of all His disciples.'
Patriarch Kirill, who had hosted his own weekly television program 'Words of a Pastor' for the past 10 years, is seen in Russia as something of a 'loose cannon' in political circles.
'Among the bishops, he's the only real politician. If I were president, I'd be afraid of such a man,' said religious affairs expert Sergei Filatov of the Russian Academy of Sciences.
Russia's politicians 'can't tell what he's going to do. If (the economy) all goes pear-shaped they don't know what Patriarch Kirill would do. They'd prefer someone they had control over,' said religious affairs analyst and journalist for the Forum 18 religious news agency, Geraldine Fagan.
Patriarch Kirill, whose crushing victory had been widely predicted, takes over a Church that had gone from strength to strength under Alexy after being repressed in the Soviet era.
Prime Minister Putin and President Dmitry Medvedev both attend church on feast days, as do other Slavic leaders such as Belarus' President Alexander Lukashenko.
Following the new Patriarch's enthronement on 1 February, Benedict sent another message, reiterating the importance of collaboration in seeking Christian unity.
The Pope recalled his meetings with the new Patriarch in Kirill's previous role as the president of the Department of External Affairs of the Moscow Patriarchate. The Pope characterised these encounters as full of 'good will' and recalled Kirill's role in 'forging a new relationship between our Churches, a relationship based on friendship, mutual acceptance and sincere dialogue in facing the difficulties of our common journey.'
Benedict also recalled the work accomplished by Kirill's predecessor, Alexy II, mentioning his efforts in the renewal of the Russian Orthodox Church, as well as its co-operation with other Christian Churches.
Alexy II, he said, 'worked assiduously for the unity of the Russian Orthodox Church and for communion with the other Orthodox Churches. He likewise maintained a spirit of openness and co-operation with other Christians, and with the Catholic Church in particular, for the defence of Christian values in Europe and in the world.
'I am certain that Your Holiness will continue to build on this solid foundation, for the good of your people and for the benefit of Christians everywhere.'