Meetings of the pair's 175,000 members will be held during July and August to approve the creation of what would be the fourth biggest co-op in the UK, with turnover of£500 million and more than 350 shops and other business units.
Although both retailers' head offices will be retained, a statement said 'it would not be sensible to guarantee that no jobs will be affected in the integration of the societies'. However, it is expected that there will be a net gain in jobs over the longer term.
Bob Burlton Oxford Swindon and Gloucester Co-op chief executive Bob Burlton will head the enlarged business until the second half of next year. Then he will hand over the reins to West Midlands Co-op's Ben Reid.
Oxford Swindon & Gloucester Co-op president Vivian Woodell said: 'Both societies share a vision to create a strong and modern co-operative movement. We are convinced the combined society will be more profitable and hence stronger than if we remain apart.'