'PETN'\ (Pentaerythritol Tetranitrate) is one of the strongest known high explosives. It is more sensitive to shock or friction than TNT or tetryl, and it is never used alone as a booster. It is primarily used in booster and bursting charges of small caliber ammunition, in upper charges of detonators in some land mines and shells, and as the explosive core of primacord.

PETN is also used as a vasodilator.

PETN formula is C(CH2ONO2)4. It melts toward 141°C. Its preparation involves nitration of pentaerythritol with a mixture of concentrated nitric and sulfuric acid.
C(CH2OH)4 + 4HNO3 -> C(CH2ONO2)4 + 4H2O