SAPO-37 containing structural chromium(III) and iron(III) ions were tested as catalysts in liquid phase oxidation of benzene and cyclohexane, using hydrogen peroxide and tert-butylhydroperoxide as oxidants. Only chromium(III) is active as oxidation catalyst. In spite of the SAPO-37 framework stability under the reaction conditions, leaching of small quantities of chromium occurs and the observed catalytic reaction is mainly due to the chromium ions in solution.