Spinels of the composition Co1-xCuxMn2O4 (x = 0.0, 0.3, 0.5, 0.7 & 1.0) have been prepared by co-precipitation technique. These were characterized by X-ray diffraction, infra-red spectroscopy, atomic absorption spectroscopy and BET method. The solid state studies such as electrical resistivity, magnetic susceptibility and electron spin resonance have been carried out and attempts have been made to correlate with the catalytic activity of the compounds. The intermediate compositions displayed better catalytic activity than the end compositions for carbon monoxide oxidation due to the phenomena of synergism. Behaviour of the activity pattern has been explained based on cation distribution in tetrahedral (A) and octahedral (B) sites. Crystallographic phase transition is observed from tetragonal to cubic at x > 0.5 by substitution of Cobalt with Copper.