Dinitrophenol (DNP) is a metabolic poison that forms proton pores (holes large enough for H+ to pass) to be formed in the inner mitochondrial membrane allowing H+ to diffuse across the membrane. Why is DNP a poison?

Dinitrophenol is a yellow crystalline compound. It undergoes sublimation and is a high explosive when dry. It is a precursor to some chemicals and is well known for its inhibition of Adenosine Triphosphate(ATP) production in cells which contain mitochondrion. It is however a poison because of its high severe toxic nature due to its ability to increase metabolism at a very rapid pace and causes very high body temperature which is the main cause of death. This very high body temperature it causes affects the cardiovascular and nervous system of the body.

This made it to be banned for consumption and is used to make other products such as antiseptics, explosives etc.