What did Popper think of Mises? The following:
“Popper was familiar with the early [sc. socialist – LK] calculation debate – Polanyi’s seminar discussed it – but not much taken by it. He knew of Mises and his circle, but it is unlikely that he read Mises closely. He strongly disliked subjectivism and libertarianism. He ‘first met Mises early in 1935 in Vienna, owing to his interest in my first book. . . . Both he and I were aware of a strong opposition between our views in the field of the theory of knowledge and methodology. Mises saw me as a dangerous opponent.’” (Hacohen 2000: 478).And this was after Popper had published his seminal book Logik der Forschung (1934; later published in English as The Logic of Scientific Discovery, 1959).
Hacohen, Malachi Haim. 2000. Karl Popper, The Formative Years, 1902–1945: Politics and Philosophy in Interwar Vienna. Cambridge University Press, Cambridge, UK and New York.