Californium(IV) oxide, also called californium dioxide, is a binary inorganic compound of californium and oxygen with the chemical formula .
Californium dioxide is produced by oxidizing californium with molecular and atomic oxygen at high pressure.
Californium(IV) oxide is a black-brown solid that has a cubic fluorite crystal structure with a lattice parameter, the distance between unit cells in the crystal, of 531.0 ñ 0.2 picometers (pm) (530.8 - 531.2).