The Roman Catholic Diocese of Caxias do Sul (Latin: Dioecesis Caxiensis Australis) is a diocese located in the city of Caxias do Sul in the ecclesiastical province of Porto Alegre in Brazil.

On Wednesday, 16 June 2010, Pope Benedict XVI appointed Auxiliary Bishop Alessandro Carmelo Ruffinoni, CS, then the auxiliary bishop to the Archbishop of Porto Alegre, as the Coadjutor Bishop of Caxias do Sul, to succeed Bishop Moretto.

• 8 September 1934: Established as Diocese of Caxias from Metropolitan Archdiocese of Porto Alegre
• 19 October 1966: Renamed as Diocese of Caxias do Sul

• Bishops of Caxias do Sul (Roman rite), in reverse chronological order
  • Bishop José Gislon, OFMCap (2019.06.26 - present)
  • Bishop Alessandro Carmelo Ruffinoni, CS (2011.07.06 – 2019.06.26)
  • Bishop Nei Paulo Moretto (1983.05.26 – 2011.07.06)
  • Bishop Benedito Zorzi (1966.10.19 – 1983.05.26)
• Bishops of Caxias (Roman Rite)
  • Bishop Benedito Zorzi (1952.06.24 – 1966.10.19)
  • Bishop José Baréa (1935.09.23 – 1951.11.19)

• Nei Paulo Moretto (1976-1983)
• Alessandro Carmelo Ruffinoni, CS (2010-2011)

• Cândido Julio Bampi, OFMCap (1957-1978)

• Neri José Tondello, appointed Bishop of Juína, Mato Grosso in 2008
• Vital Corbellini, appointed Bishop of Marabá, Para in 2012
• Adelar Baruffi, appointed Bishop of Cruz Alta, Rio Grande do Sul in 2014
• Leomar Antônio Brustolin, appointed Auxiliary Bishop of Porto Alegre, Rio Grande do Sul Brazil in 2015

• GCatholic.org
• Catholic Hierarchy
• Diocese website (Portuguese)

29°10′08″S 51°10′46″W / 29.1690°S 51.1794°W / -29.1690; -51.1794