Nuneham Viaduct, also known as Nuneham Railway Bridge and the Black Bridge is near the town of Abingdon-on-Thames in Oxfordshire, England. It is a two-span, bowstring truss bridge that carries the Didcot to Oxford section of the Cherwell Valley Line across the River Thames between Abingdon Lock and Sandford Lock. Its name is derived from the neighbouring Nuneham House. The total length is 99 yards (91 m); the southern and northern ends are respectively 57 miles 24 chains (92.22 km) and 57 miles 29 chains (92.32 km) from Paddington.

The Cherwell Valley line is the railway line between Didcot and Banbury via Oxford. It links the Great Western Main Line and the south to the Chiltern Main Line and the Midlands. The line follows the River Cherwell for much of its route between Banbury and Oxford.