Qo'noS was located in the Qo'noS system and had one moon, Praxis. The system was in Sector 70 (the Qo'noS sector) in block 27, the Omega Leonis sector block, in the Beta Quadrant. The exact coordinates of the planet were 43.89.26.05 in grid 09, quad 68, block 27, sector 70. Qo'noS was about four days away from Sol at Warp 4.5 and was less than ninety light years from the Sol system.
- Main article: Klingon history
As the homeworld of the Klingons and the capital world of the Klingon Empire, Qo'noS housed the Klingon High Council and other important institutions. Qo'noS had achieved interstellar travel capability around the time of Kahless in the 9th century. Warp capability was achieved some time after 1947 and Warp 6 had been achieved some time before 2152. Using the Vulcan star charts, Qo'noS was first visited by Humans in 2151.
In the alternate reality, prior to 2259, the sole moon of this planet, Praxis, was destroyed by an unknown catastrophic event which fragmented the moon. Qo'noS was visited by Khan Noonien Singh and the USS Enterprise in 2259, culminating in a battle between Klingon patrol troops, officers from the Enterprise and Khan.
In 2293, the ozone layer on Qo'noS was severely damaged when Praxis, a key energy-production facility for the Klingon Empire, exploded after an accident involving over-mining, its destruction sending out a subspace shock wave. This event forced planning for the evacuation of Qo'noS and led to the signing of the First Khitomer Accord with the Federation.