Onsala Space Observatory is the Swedish National Facility for radio astronomy.

The observatory operates the two radio telescopes in Onsala, 45 km south of Göteborg, in the mm and cm wavelength regions, and is one of three partners in the APEX telescope in Chile. The main scientific focus is on the origins of stars and galaxies using high frequency spectroscopy and high resolution observations in radio astronomy, and the application of these techniques in Earth/environmental science. The full effort is supported by research and development in millimetre/submilimetre receiver technology. The development of new receivers is another important part of the observatories research.