Soyuz 12 was a crewed test flight of the newly redesigned Soyuz 7K-T. The flight marked the return of the Soviets to crewed space operations after the 1971 accident. The crew capacity of the capsule had been decreased from three to two cosmonauts to allow for pressure suits to be worn during launch, re-entry and docking.

As the first crewed test of the new version of the Soyuz, Soyuz 12 was to have flown to a Salyut station. But the failures of Salyut 2 and Cosmos 557 in the months previous meant there was no station for the craft to dock to. The service module had no solar panels, carrying batteries for power instead, which limited the flight to about two days, enough time for a journey to and from a space station.

After the successful launch, the craft was maneuvered to a 326 x 344 km orbit on the second day in space, which later proved to be the standard orbit for the Salyut 4 space station. A multispectral camera in the orbital module was used in coordination with aircraft to photograph the Earth. It was reported that the intention of the camera was to survey crop and forest conditions The cosmonauts also utilised the Molniya 1 satellite to communicate with ground stations when out of range.

The crew landed safely on 29 September.

This is Soyuz's 20th flight, and 11th crewed flight.

The Soyuz is a Soviet crewed spaceship, developed to made manned lunar missions. This version called 7K will fly 4 times on the giant launcher N1, and several tens of times on Proton to fly over the Moon, which will be successful during the mission Zond 4. Soyuz will become the first spacecraft to transport living beings to the Moon during the flight of Zond 5, with two turtles. Subsequently, it is adapted to low orbit and will fly on the Soyuz launcher to serve the Salyut and Mir stations and the ISS.

A large object was jettisoned when Soyuz 12 was preparing for retrofire. The object remained in orbit for 116 days, landing 400 km southwest of Karaganda.