A few months after being dismissed from the government, Diallo was appointed as Ambassador to Austria. He presented his credentials to Austrian President Heinz Fischer on 8 January 2009. In addition to serving as Ambassador to Austria (based at the Burkinabé embassy in Vienna), Diallo was given additional accreditation for Croatia, Hungary, the Czech Republic, Slovakia, and Slovenia, as well as various international organizations: the International Energy Agency, the United Nations Office at Vienna, the United Nations Industrial Development Organization (UNIDO), and the Preparatory Commission for the Comprehensive Nuclear Test Ban Treaty Organization. Diallo, along with a number of other prominent figures in the CDP, announced his resignation from the party on 6 January 2014. Those who resigned said that the party was being run in an undemocratic and damaging manner, and they expressed opposition to plans to amend the constitution to eliminate term limits, which would allow President Blaise Compaoré to stand for re-election in 2015. A new opposition party led by the prominent CDP members who resigned, the People's Movement for Progress (MPP), was founded on 25 January 2014. Roch Marc Christian Kaboré was designated as President of the MPP and Salif Diallo was designated as its First Vice-President. Kaboré, standing as the MPP candidate, was elected as President of Burkina Faso in the November 2015 general election, while Diallo was elected to the National Assembly as a candidate on the MPP's national list. Kaboré was sworn in as President of Burkina Faso on 29 December 2015, and the National Assembly elected Diallo as its President on 30 December. He received the votes of 78 deputies, while 43 voted for Adama Sossou, a deputy from the Union for Progress and Reform. Diallo received medical treatment in Tunis and then went to Paris, where he died on the night of 18–19 August 2017 at the age of 60.