DNO ASA operates exploration and production fields with a focus on the Middle East and North Sea. The company is organized into country-based divisions. The company is publicly held with shares listed on the Oslo (DNO) exchange. DNO was originally an abbreviation of Det Norske Oljeselskap.
DNO was formed in 1971 and listed on the Oslo stock exchange in 1981. New management in 1996 focused investments outside of Norway with the group entering Yemen in 1998. In 2004, it was the first international company to enter the Kurdistan region of Iraq. In 2007, DNO's Norwegian interests were sold to Pertra which took the name Det Norske Oljeselskap while DNO was renamed DNO International. DNO International was renamed DSO in 2014. In 2018, Origo Exploration was acquired from Riverstone Holdings.