The adsorption characteristics of CO on Co3O4 nanostructure on various sites are studied using density functional theory and reported. The structural stability of Co3O4 base material is studied using formation energy and vibrational analysis. The most significant parameters such as adsorption energy, energy gap, average energy gap variation and Mulliken charge transfer are taken into count to study the favourable adsorption site of CO on Co3O4 base material. Moreover, the incorporation of In atoms in Co3O4 nanostructures enhances the adsorption characteristics of CO on Co3O4 base material. The findings of the present work infer that pristine and In substituted Co3O4 nanostructures can be used to detect low concentrations of CO in the atmosphere. (C) 2016 Elsevier B.V. All rights reserved.