From 1948, Kropfreiter spent his school years at the Catholic Episcopal Gymnasium Petrinum, where he received his first basic musical education. Immediately after graduating from high school, he entered the Augustinian Canonry of St. Florian in 1953; because of his extraordinary musical talent, the status of choir brother was established for him, as Kropfreiter had not studied theology and was not an ordained priest. At the monastery, he was initially taught music theory by the organist Johann Krichbaum. From 1955 to 1960, he studied composition and organ at the Bruckner Conservatory in Linz and at the Vienna Music Academy. After completing his musical studies, he was appointed monastery organist in St. Florian; he held this position until his death. For a time, he was also a teacher of the St. Florian Boys' Choir and from 1966, director of the monastery choir (Regens Chori). He died in St. Florian in 2003 at the age of 68. Kropfreiter created an extensive organ work, making him one of the most important Austrian organ composers of the 20th century. He helped the St. Florian monastery to become even more well-known. He composed several orchestral works (including organ concertos, 3 symphonies), masses, church music, choral music, chamber music and organ music pieces (including Toccata francese, Signum, numerous chorale arrangements of varying difficulty), with which he became well-known not only in Austria. In his compositions, he placed great importance on polytonality and Hindemith's counterpoint.