Born exactly 100 years ago, Friedrich Hayek played a major role in the reconstruction of an original liberal way of thinking, opposed in particular to Keynesian interventionism. This article retraces the itinerary of this man who, initially defeated by Keynes, saw his ideas triumph in the latter years of his life. The author then discusses the foundations of Hayek's liberalism, with particular attention to his conception of knowledge and theory of spontaneous orders, upon which was based his rejection of socialism and planning. Lastly, he examines Hayek's conceptualisation of the State and relations between the State and the economy, and shows that Hayek's liberalism has, in the context of current liberal thinking (which is often characterized as neoliberal), a singular characteristic distinguishing it from other currents.