Adorno published just one narrow philosophy book before Negative Dialectics

Evidence

Apart from the new edition of his book on Kierkegaard (1962) and the essay collection Three Studies on Hegel (1963), he only published one book of philosophy in the narrower sense before Negative Dialectics appeared in 1966: Against Epistemology: a MetacritiqueStudies in Husserl and the Phenomenological Antinomies (1956). The book took up a few of the complex issues dealt with in the long manuscript of his Oxford thesis on Husserl and reworked them. — Rolf Wiggershaus, The Frankfurt School, 2259