Coaxium, known by alternative names such as Corellian hyperfuel or simply hyperfuel, represented a scarce form of hypermatter and a notably valuable type of starship fuel that was extracted from the planet Kessel.
In its natural, unprocessed state, coaxium was an extremely unstable and powerfully explosive type of hypermatter. To achieve sufficient stability for storage at ambient temperatures, it required a refining process. Even after refinement, coaxium demanded careful handling due to its inherent explosiveness. Upon extraction, unrefined coaxium would gradually destabilize, changing color to red before detonating violently if not properly stored within a climate-controlled setting. A refinery dedicated to coaxium processing existed on the desert planet of Savareen. The market value for 100 kilograms of refined coaxium was approximately 60 million credits.
The hyperdrive reaction chamber in starships utilized a coaxium coating. When energized, this coating enabled interstellar travel via hyperspace. Coaxium's exceptional energy generation capabilities meant that only a small quantity was needed to power an entire fleet of vessels. This characteristic contributed to its high value and made it a highly sought-after resource. The Galactic Empire implemented stringent security measures for the transportation of significant coaxium shipments, intending to monopolize its production.
Scientists, leveraging knowledge of purrgil and the gas Clouzon-36, determined that coaxium formed naturally in areas of intense interstellar energy, such as Kessel.
During the era of the Galactic Empire, coaxium's great value made it a target for both the Empire and various criminal organizations, including the White Worms, the Pyke Syndicate, and Crimson Dawn.
Thirteen years before the Battle of Yavin, a young Han managed to acquire a small quantity of coaxium. He and his childhood friend Qi'ra planned to use it as a bargaining chip to secure their departure from Corellia. However, his plan was only partially successful, as he only managed to escape himself, while Qi'ra was captured at the spaceport. Three years later, Solo found himself involved in a plot to steal a shipment of the valuable fuel from a 20-T Railcrawler conveyex transport on Vandor, on behalf of Dryden Vos and Crimson Dawn. Due to the intervention of Enfys Nest and her Cloud-Riders, Solo chose to sever the tethers securing the coaxium container, rather than following Tobias Beckett's instruction to fly directly into a mountainside. The Cloud-Riders' swoops were unable to support the container's weight and were forced to release it, resulting in a massive explosion that caused the mountainside to collapse.
Eventually, Solo, along with Qi'ra, Lando Calrissian, the Wookiee Chewbacca, and L3-37, undertook the Kessel Run to obtain unrefined coaxium from the Pykes and deliver it to Vos as compensation for their earlier failures. This time, Solo succeeded, transporting the shipment to Savareen for refining. He and his associates were soon confronted by the Cloud-Riders, who exposed Crimson Dawn's plan to use the coaxium to inflict widespread destruction across the galaxy.
Solo decided to betray Crimson Dawn, providing Beckett with false information, knowing Beckett would betray him to Vos, claiming he would be delivering two crates of counterfeit coaxium, when in reality, he was transporting the genuine shipment. Both Beckett and Vos were deceived by his ploy, as the Crimson Dawn enforcers attempted to ambush the Cloud-Riders, only to be tricked by decoys and empty crates before being defeated. Beckett then took Chewbacca hostage, holding him at blasterpoint to force him to carry the coaxium off Vos's yacht, but Solo soon caught up and killed Beckett. Subsequently, he gave the coaxium to the Cloud-Riders to support their growing rebellion. After declining Enfys's invitation to join them, she gave him a single vial of coaxium, which he then used in a sabacc game against Calrissian, winning ownership of the Millennium Falcon.
Some time after the Battle of Yavin, the MC80 Star Cruiser Aurora Flare was transporting a large quantity of coaxium from the Redhurne system. Upon learning of the murder of king Lee-Char, the Aurora Flare crashed into an Imperial-class Star Destroyer, creating an opportunity for numerous other Mon Calamari cruisers to escape to the rebel-controlled Mako-Ta Space Docks.
Following the Galactic Civil War, the racer Marcus Speedstar refueled his racer with hyperfuel. However, he underestimated the effect it would have on his ship, causing his racer to lose control, crashing into the stands, and killing his sister-in-law and niece.
Speedstar's older brother Jarek Yeager stored a container of hyperfuel in his private hangar. Jace Rucklin and his team had wanted to steal it for a long time, since it gives the racer a boost. They managed to persuade Kazuda Xiono to assist them, but the team was unaware that the fuel's drops could transform a ship into a massive bomb. While Xiono managed to save Rucklin, his racer exploded and Rucklin vowed revenge on Xiono.
Following the Evacuation of D'Qar, Kazuda Xiono guided the Warbird gang to raid the remains of the Fulminatrix in order to recover its coaxium for the Colossus.