Dihexalon gas, a substance with lethal effects on the majority of living organisms, was harnessed in the production of biochemical weaponry. Its development took place in the time period preceding the Clone Wars, and its deployment in combat was infrequent.
The year 25 BBY saw its utilization in the creation of a bioweapon that the criminal mastermind "Striker" (a pseudonym employed by Granta Omega) tried to release upon the world of Mawan.