The town was established by Benedictines from Postoloprty in the 12th century. They built a monastery there, which was destroyed in the 13th century. The village kept the name of Klösterle, i.e. little Kloster in German, and klaster in Czech.
In the years to come after the foundation of the second porcelain manufacture 1794 Klasterec nad Ohří has gown up in importance and became more and more famous in the whole region. In the town there is still a porcelain production until today under the trade market name THUN 1974 a.s.. However, the owner of the Klasterec nad Ohří – Porcelain manufacture Thun und Hohenstein was in 1945 disposed and banished.
Rašovice
Rašovice is a small village on the way to Kadaň on the right bank of the river. It was called Rošovice (after the name of Roch) until 1924. Having been separate until 1961, the village is now part of Klasterec nad Ohří. There are ruins of Lestkov castle above the village.
The village was first recorded in 1443 as a part of the Egerberg domain and with the domain changed holders from Fictums to Lobkowitz of Hasištejn. Bohuslav Felix of Lobkowitz built a castle in the village in 1581 and called it Felixburg. With a new master - Christoph Simon von Thun (cz:Kryštof Šimon), 1623, after the Battle of White Mountain - the village became part of the Thun's domain. St. Anna Church was finished 1837 to replace the previous chapel. In 1871 the villagers rose against the construction of a new bridge over the river, and after a skirmish with the Italian workers they had to be pacified by the army.
The population was 296 in 1863, 587 in 1930 and 104 in 1991
