Sio

• Sió, an artificial channel in Hungary
• Siø, a small Danish island in the South Funen Archipelago
• Sio, Burkina Faso, a village in Burkina Faso
• Sio, Mali, a commune in Mali
• Sio, Papua New Guinea, a town in Papua New Guinea
• Sio, a river in Western Africa providing water for the Lake Togo
• Smithton Airport (IATA airport code), Tasmania, Australia

• SIO (software), a serial port driver for the OS/2 operating system
• Atari SIO, a peripheral bus
• Super I/O, a motherboard chipset component
• Start I/O (SIO) instruction on IBM S/360 or S/370.

• Scripps Institution of Oceanography, La Jolla, California, U.S.
• Students Islamic Organisation of India
• Foundation for Student Life in Oslo (Studentsamskipnaden i Oslo)
• Sexarbejdernes Interesse Organisation, a Nordic organization of sex workers (see Prostitution in Sweden)

• Sio (cartoonist), Italian comics artist
• William Sio (born 1960), New Zealand politician
• David Sio (born 1962), Samoan rugby union footballer
• Giovanni Sio (born 1989), Ivorian international footballer
• Ken Sio (born 1990), Australian rugby league player
• Michael Sio (born 1993), New Zealand rugby league player

• Battle of Sio, part of the New Guinea campaign of World War II
• ISO 639:sio or Siouan, a language family of North America
• Sio language, an Austronesian language
• Sio (genus), a genus of fish
• SiO, the chemical formula for Silicon monoxide
• SiO2, the chemical formula for Silicon dioxide
• Senior Investigating Officer, the lead officer in a criminal investigation in the U.K.

• De Sio, a surname

{{disambiguation|geo|surname}}