OPDO was founded on March 26, 1990 in North Shoa, Dera District at Gundomeskele. The founding members of OPDO were: those Oromo fighters who had been in the Ethiopian People's Democratic Movement, those who had refused the Derg regime which had forced them to fight, and by those Oromo origin intellectuals who had been work in the Northern part of Ethiopia. Not more than 37 member of OPDO facilitate the establishment of the OPDO. This number in short period of time reached to 170. It takes more than seven months to establish OPDO. The foundational congress held in liberated area of Tigray at Adet woreda. After its establishment, OPDO joined EPRDF forces.