A novel technique involving the pyrolysis of an ultrasonically atomized solution has been used to prepare finely dispersed submicron sized spinel-type Cu1.1Mn1.9O4 powders with spherical morphology. The decomposition temperature of the aerosol as well as the total concentration of the solution have been varied to study the influence on the structural, thermochemical and morphological features. Together with X-ray diffractometry (XRD), thermal analysis (TA), and X-ray photoelectron spectroscopy (XPS) results it became obvious that the Cu1.1Mn1.9O4-spinel exists in a metastable state. Turnover-rates of catalytic CO-oxidation with molecular oxygen near room temperature gave good yields, but depended on the activation procedure of the spinel.