Kinetics of carbon monoxide oxidation over Zn1-xCuxMn2O4 (x = 0.0, 0.3, 0.5, 0.7, 1.0) prepared by co-precipitation method has been studied in the temperature range 373-673 K. Results have been discussed in the light of X-ray powder diffraction, atomic absorption spectrometry, gas chromatography, electrical conductivity, magnetic susceptibility, electron spin resonance and surface area measurements. Higher activity of intermediate compositions is due to the co-operative effect of two different A-site metal ions and crystallographic phase transition.