PETN (Pentaerythritol Tetranitrate, also known as Penthrite) is one of the strongest known high explosives, with a relative effectiveness factor (R.E. factor) of 1.66. 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 detonation cord, detonating at a rate of 7000ms^-1.

PETN is also used as a vasodilator.

PETN's formula is C(CH₂ONO₂)₄. Its density is 1.773 g/cm³. It melts toward 141°C. Its preparation involves the nitration of pentaerythritol with a mixture of concentrated nitric and sulfuric acid.
C(CH₂OH)₄ + 4HNO₃ → C(CH₂ONO₂)₄ + 4H₂O