Oskar Kraus was born in Prague on 24 July 1872. After attending the German State School (Staatsgymnasium) Kraus began studying the philosophy of law at Prague in 1890. His philosophical teachers were Anton Marty and Friedrich Jodl. It was through Marty that Kraus first fell under the significant intellectual influence of Franz Brentano whom he met for the first time in 1893. Graduating from Prague in 1895 Kraus sought a career at the Finanzprokuratur in 1896. In 1902 he earned completed his habilitationsschrift on The Theory of Value: A Benthem Study.
During this time Kraus became a member of the Louvre circle formed around Marty and became a lawyer in 1907. With a full professorship in 1916 he succeeded Marty as professor of philosophy at the German university in Prague. Starting in 1922 and continuing for the rest of his life Kraus with Alfred Kastil undertook the considerable task of editing Brentanos main works and fragments most notably the third volume of Psychology from an Empirical Standpoint published as Sensory and Noetic Consciousness (1928). With the financial assistance of President Masaryk Kraus also established the Prague Brentano Society.
In addition to his editions of Brentanos works Krauss publications are many and include treatments of Aristotelian and Platonic philosophy (1905 1913) Albert Einstein and relativity (1925) and Francis Bacon and Jeremy Bentham on freedom (1926). The only publication of his available in English is Albert Schweitzer: His Work and His Philosophy (trans. E. G. McCalman 1944).
With the invasion of German troops in Prague in March 1939 Kraus was arrested. Released after six weeks in prison he fled to Great Britain where he lived until dying of cancer on 26 September 1942 in Oxford.