The Matilija Sandstone (/məˈtɪləhə/) is a sedimentary geologic unit of Eocene epoch in the Paleogene Period, found in Santa Barbara and Ventura Counties in Southern California.

[2]: 25–26 The type locality of the unit is at Matilija Hot Springs, along the Ventura River about ten miles (16 km) northwest of Ojai, near to California State Route 33.

[2]: 26  The unit can be found along the crest of the Santa Ynez range all the way from the western extremity of the mountains near Point Arguello, to its type locality north of Ojai, and east and northeast into the Ventura County backcountry, where Piru and Sespe creeks cross through the formation.

[8]: 667 Sometime in the early Eocene, around 50 million years ago, the landmass containing present-day Santa Barbara County became submerged, allowing sediment deposition offshore.

[9][3] After reaching its current position along the coast, the entire Santa Ynez Range was uplifted, mostly during the Quaternary period and late Pliocene, by crustal shortening and compression from tectonic forces at the boundary of the Pacific and North American Plates.

[11] Since this deep-lying play is incompletely explored, with many boreholes not even reaching the Matilija, the estimates for hydrocarbon resources are speculative, with the United States Bureau of Ocean Energy Management, Regulation and Enforcement giving a range of 117 to 127 million barrels (18,600,000 to 20,200,000 m3) of oil recoverable using current technology for the entire Santa Barbara-Ventura Basin Province.

[11] The largest single hydrocarbon accumulation yet identified in the Matilija Sandstone is in the Molino Offshore Gas Field, discovered in 1983, and contains approximately 39 million barrels (6,200,000 m3) of oil equivalent.