Graduated from the Reykjavík College of Music in 1985. Subsequently he continued his studies in the USA where he finished Master's degrees from California Institute of the Arts and Yale University. Between 1992 and 1995 he worked as a guest composer at the studios of Stanford University and U.C. Berkeley in California. His works span a large range, from solo instrumental pieces to computer controlled dance pieces. They have been released on CDs and performed all over the world. Thordarson has received a working grant from the Icelandic government in 1994 and 1998, and the DV cultural prize for organizing the ART2000 computer music festival in Iceland. He is co-director of the Kopavogur Computer Music Centre, besides teaching computer music at Iceland Academy of the Arts.