Ysgol Gyfun Rhydywaun is a Welsh-medium comprehensive school in the Cynon Valley in the village of Penywaun, Rhondda Cynon Taf, Wales, to the northwest of the town of Aberdare. The school was established on 1 September 1995. It provides a Welsh-medium education for pupils from the Cynon Valley and from neighbouring Merthyr Tydfil County Borough, where there is no Welsh-medium secondary school.