Kolarz was born in Teplitz-Schonau, Kingdom of Bohemia, Austro-Hungarian Empire. He studied at Charles University in Prague, then moved to Berlin to work as a journalist. However, he was expelled by the Nazis in 1936. He moved to Paris, before fleeing to London in 1940.
Kolarz married Alexandra Lipovsky in 1939 (she died in March 2000) and they had one son.
A number of Kolarz' books were compiled by others in the wake of his early death.
- Stalin and Eternal Russia, 1944
- Myths and Realities in Eastern Europe, 1946
- Russia and Her Colonies. Frederick A. Praeger, New York. 1952
- How Russia is Ruled, 1953
- The Peoples of the Soviet Far East, 1954
- Religion in the Soviet Union, 1961
- Religion and Communism in Africa, 1963
The Times, obituary 23 July 1962