It was found that the KV-2 was much to heavy and were eventually replaced by self propelled guns.
The Germans found that if they immobilized the Kv-2 by damaging it tracks they had a easier time destroying it.
Trials in Finland
Used against the Mannerheim Line in February 1940.
The KV-2s suffered from mechanical problems and often broke down. The 41st Tank Division reported that it lost 2/3 of its 33 KV-2s, but only five of those were due to combat.
KV-2s were used in the defense of Moscow in late 1941.
The 62nd Army, commanded by Major-General V. Chuikov, had KV-2s to help in the defense of Stalingrad.