Clancium oxide was a medium-yield explosive. The explosive was used for high-volume heat generation in emergency situations. It was preferred over sarium krellide in low-pressure atmospheres because of superior thermal dispersion characteristics. However, it was not recommended that this explosive be used in class H and class N(2) environmental conditions. In 2367, this explosive was stored on aboard the Federation starship USS Enterprise-D.
In that year, clancium oxide was on a list of explosives that Lieutenant Commander Data and Counselor Deanna Troi searched through in an attempt to find one that could produce enough energy to release the Enterprise-D and an alien ship from the Tyken's Rift. (TNG: "Night Terrors")