Sunol (formerly, Sunolglen) is an unincorporated census-designated place (CDP) in Alameda County, California, United States. The population was 913 at the 2010 census.
The small, rural town of Sunol located along Niles Canyon is well known for its historic railroad system, on which the tourist railroad Niles Canyon Railway makes an in-town stop and the Altamont Commuter Express passes en route to San Jose and the Central Valley.
The first Sunol post office opened in 1871 and the name was changed to Sunolglen the same year. The name reverted to Sunol in 1920. The town's name is in honor of Antonio Suñol, part owner of the historical Rancho Valle de San Jose land grant that once contained the site of the town.