The KS-12 is a towed anti-aircraft gun of Soviet origin. It was developed in 1939 to replace the 76.2mm weapon that was developed a year earlier. The KS-12 was one of the major high altitude anti-aircraft guns in Soviet service during World War 2. The ordnance of the KS-12 also served as the basis for the ordnance used in the SU-85 assault gun and T-34/85 tank.

The KS-12 is consists of a large 85mm cannon fitted on a turntable on a four wheel chassis. In the firing position the weapon rests on jacks and outriggers. A gun shield is fitted to most units as the KS-12 also has a secondary role as a direct fire weapon. The KS-12 is manually loaded and traverse and elevation are manual as well, resulting in a crew of 7. Fire control is normally provided by a PUAZO-6 o -12 fire director and SON-9 fire control radar.

The KS-12 fires fuzed 85mm fragmentation ammunition against aircraft and armor piercing rounds against armored vehicles. Since it is manually loaded the rate of fire is only 15 to 20 rounds per minute. The KS-12 has a maximum horizontal range of 15.5 km and vertical range of 10.5 km. The longer barreled M1944 may reach 18 km and 11.6 km respectively. Against ground targets the maximum range is about 8 km.

The KS-12 is a very heavy system that cannot be moved by hand. It is normally towed by a ZIL-157 or other 6x6 truck. The truck also transports the crew and usually carries 150 rounds of ammunition. The PUAZO fire director and SON-9 fire control radars are also towed by truck.

The KS-12 was widely used by Soviet forces during World War 2 and is claimed to have taken out over 4.000 Axis aircraft. After the war it was soon replaced in russia by the KS-19 and KS-30, but remained in use with other Eastern European nations and was widely exported. China produced the KS-12 under license and Soviet export models were common in Asia, the Middle East and Africa during the Cold War. Nowadays the KS-12 is only found in active use in third world nations.