The Kilji language served as the mode of communication for the Kilji species. During 18 BBY, General Crofyp, a Kilji national belonging to the Kilji Illumine, utilized the language on his Kilji war cruiser, the Anvil, while conversing with Vassal Two, who operated the warship's sensor systems. Subsequently, Crofyp was heard using the language while the cruiser underwent an attack from the Chiss heavy cruiser, Springhawk.
The 2021 novel Thrawn Ascendancy: Lesser Evil, which concluded Timothy Zahn's Ascendancy Trilogy, featured the Kilji language.