A molecular decay detonator is a type of device used in Romulan explosives.

In 2367, Duras used a molecular decay detonator in an explosive used to disrupt the Sonchi ceremony held to verify Chancellor K'mpec's death. However, because this type of detonator was only used by the Romulans, it exposed Duras's relationship with the Romulan Empire. (TNG: "Reunion")