Didcot is a railway town and civil parish in South Oxfordshire, England, located 15 miles (24 km) south of Oxford, 10 miles (16 km) east of Wantage and 15 miles (24 km) north west of Reading. Historically part of Berkshire, the town is noted for its railway heritage, Didcot station opening as a junction station on the Great Western Main Line in 1844. Today the town is known for the railway museum and power stations, and is the gateway town to the Science Vale: three large science and technology centres in the surrounding villages of Milton, Culham and Harwell.

South Oxfordshire is a local government district in the ceremonial county of Oxfordshire, England. Its council is temporarily based outside the district at Abingdon-on-Thames pending a planned move to Didcot, the district's largest town. The areas located south of the River Thames are within the historic county of Berkshire.