Sydenham is a village and civil parish in the South Oxfordshire District of Oxfordshire, England, about 3 miles (5 km) southeast of Thame. To the south, the parish is bounded by the ancient Lower Icknield Way, and on its other sides largely by brooks that merge as Cuttle Brook, a tributary of the River Thame. The 2011 UK census recorded the parish's population as 451.
Until the 20th century the parish was almost entirely agricultural. By the 1950s numerous people from Sydenham were working at Chinnor Cement Works, but this closed in 1989.
For more information, see the EN Wikipedia article Sydenham, Oxfordshire.