Zheleznogorsk (Russian: Железного́рск), is a closed town in Krasnoyarsk Krai, Russia, with a developed nuclear industry.

Defense plants included nuclear facilities built within caverns excavated in the granite mountain on the northern edge of the city, as well as space research enterprises.

Zheleznogorsk is located 35 km north of Krasnoyarsk, in the foothills of the Atamanovsky Ridge, the spurs of the Sayan Mountains.

Due to the high continentality of the climate, there are large temperature differences during the day and at night, as well as between winter and summer.

The climate of the city is considered warmer than in Krasnoyarsk itself due to the lower elevation difference and greater penetration of warm western and southern air masses into the West Siberian Plain and the Yenisei Valley.

Zheleznogorsk is also the location for the production of plutonium, electricity and district heat using graphite-moderated water-cooled reactors.