In the eastern city of Kharkiv, three people froze to death overnight. In the capital, Kyiv, 35 people were hospitalized.
Ukraine's fuel and energy ministry says the harsh weather has left more than 600 towns and villages without electricity.
In Russia, the cold has in the past 24 hours killed five people in Moscow and resulted in 19 being hospitalized. Construction work in the city has had to be suspended due to temperatures that remain below minus 20 degrees Celsius.
Authorities in the Russian republic of Tatarstan say two people died in Kazan and another two in different locations.
Russian meteorologists say they expect temperatures in Western Siberia to plunge below minus 40 in the coming days. Seasonal temperatures in the region are generally around minus 20 degrees.
(ITAR-TASS, RIA Novosti, Interfax-Ukraina, Unian)