Born in Brăila, Romania in 1922 to Greek parents, at the age of 10 he moved with his family to Greece, where he later began studying architecture and engineering in Athens. He interrupted his studies in 1941, due to the invasion of his country by the Nazis. He took part in the Resistance during the Second World War and in the first phase of the Greek Civil War as a member of the student company Lord Byron of the Greek People’s Liberation Army (ΕΛΑΣ – Ellinikós Laïkós Apeleftherotikós Stratós). In 1945, he was wounded in the face by a howitzer explosion, sustaining very serious injuries that left him partially disfigured and also causing the loss of an eye. In 1946, he was able to complete his studies and obtain the title of engineer, but as a result of his political activities during the war, he was severely persecuted (he was even sentenced to death later on), which is why he decided to emigrate: thanks to a forged passport, he managed to arrive in France in 1947. He settled in Paris and in 1948 started working for architect Le Corbusier’s office as an engineer. He soon began to collaborate in the design of several important works in which the firm was involved at that time, such as the housing units in Nantes (1949) and Briey-en-Forêt, the Bagdad Cultural Centre (1957), the La Tourette Convent (1953) and the famous Philips Pavilion for the Brussels Trade Fair (1958), which was the venue for the first performance of Edgard Varèse’s Poème Électronique. The structure of the Pavilion was in fact based on the same formal concepts that Xenakis had already used in his piece Metastaseis, which he had composed four years earlier. The ‘dual’ nature of these works (‘Metastaseis’ and the Philips Pavilion) is an example of Xenakis’ meta-artistic theory, according to which an artistic expression based on mathematical calculation can be realised regardless of the type of media used. It was shortly after his arrival in Paris that Xenakis began his studies in composition, initially under the guidance of Arthur Honegger and Darius Milhaud, with whom, however, he had uneasy relations and soon found himself in conflict regarding their teaching methods.
Starting in 1951, he was a pupil of Olivier Messiaen, whose analysis courses he assiduously followed at the Conservatoire Supérieur de Paris. In this way, he was able to increase his awareness, along with his technical compositional skills, to the point that he soon began to apply the mathematical and architectural concepts developed in Le Corbusier’s studio with purely musical material, a direction that Messiaen himself advocated. In 1955, conductor Hans Rosbaud conducted the first performance of his piece Metastaseis at the Donaueschingen Festival; this piece and those that followed (Phitoprakta in 1956 and Achorripsis in 1957), together with the articles that Xenakis published in ‘Gravesaner Blätter’, the musicology journal edited by Hermann Scherchen, gave Xenakis international notoriety, which finally allowed him to devote himself exclusively and totally to composition. In 1963, he published ‘Musiques Formelles’ (later revised and expanded in 1971 and 1990), a collection of his essays on his musical ideas and personal compositional techniques. As a pioneer of the use of computers in the field of ‘algorithmic composition’, Xenakis founded the CEMAMu (Centre d’Études de Mathématique et Automatique Musicales) in 1966, an institute dedicated to the study of computer application in music, where he later conceived and developed the UPIC system, which allows the direct aural realisation of the graphic notation of geometric shapes. He also founded an institute with similar intentions at Indiana University in Bloomington (USA). From 1975 to 1978, he was professor of composition at Gresham College in London, where he also gave numerous public lectures.