Tolium, a gas suitable for storage within canisters, had a notable property. Specifically, a potent toxin resulted from the combination of tolium gas and cyphrite. During 3 ABY, Lando Calrissian facilitated the surreptitious transport of the scoundrel Kay Vess to the secret location of Imperial Governor Thorden, concealing her in a crate and presenting it as a gift consisting of tolium gas canisters.
The initial canon reference to tolium occurred within the "Wild Card" expansion pack for Star Wars Outlaws, a video game developed by Massive Entertainment, and its launch date was November 21, 2024.
Before its inclusion in the canon, tolium debuted in the Star Wars Legends continuity within the Star Wars: The Roleplaying Game adventure titled "Seregar Turnabout", which was included in the 1997 No Disintegrations sourcebook.