Dioxis

Dioxis was a potent toxic gas used by the Neimoidians of the Trade Federation at the time of and following the Battle of Naboo. The green-white gas was deadly to most carbon-based lifeforms.

When Jedi Master Qui-Gon Jinn and his Padawan Obi-Wan Kenobi were sent by Supreme Chancellor Valorum to negotiate the blockade of Naboo, the ambassadors were double-crossed by Nute Gunray. The Neimoidians released dioxis gas via gas emitters into the Saak'ak conference room where the Jedi waited. However, their command of the Force afforded them a sense of the danger, and were able to survive in the toxic environment until a squad of security battle droids arrived with orders to dispose of their bodies.

Thirteen years later, on Cato Neimoidia, Obi-Wan Kenobi identified a toxic gas released by Nute Gunray's mechno-chair as dioxis—though this toxin was also identified as swamp gas, the chemical weapon used by the Separatists on Ohma-D'un earlier in the Clone Wars.

Around 21 BBY, dioxis was used as part of a contest arranged by Count Dooku on his homeworld of Serenno. Within a construct known as The Box, eleven bounty hunters competed in a series of tasks to prove their worthiness to be part of a team that would abduct Supreme Chancellor Palpatine on Naboo. The first task involved the competitors having to escape a room that was filling with dioxis gas.

Text and facts from the “Dioxis/Legends” article on Wookieepedia, licensed under CC BY-SA 3.0. Modified for this site.