Co3O4 nanoparticles (NPs) assembled coatings were synthesized using pulsed laser deposition (PLD) by taking advantage of phase explosion process. The coatings were prepared at substrate temperature of 150 C by using three different laser fluences (3, 5, and 7 J/cm(2)) in order to tune the size of NPs. Structural property and surface morphology of NPs were investigated by Raman spectroscopy and electron microscopy respectively. The catalytic activity of these Co3O4 NPs coatings was tested for dye degradation as well as for CO oxidation. Co3O4 coating (3 J/cm(2)) was able to completely degrade Methylene blue dye with significantly high rate, via photo Fenton reaction under visible light irradiation, as compared to Co3O4 powder catalyst mainly owing to the size and nanocrystalline nature of NPs on the catalyst surface. Coating synthesized at low laser fluence (3 J/cm(2)) showed best catalytic activity. This particular coating also showed above 90% conversion efficiency of CO to CO2 at 250 degrees C with very high specific rate. The special features of NPs, such as narrow size distribution, small average size (5-20 nm), perfect spherical shape, low degree of agglomeration, and nanocrystalline phase, are the main factors responsible for the enhanced catalytic activity of the PLD produced Co3O4 NPs assembled coating. (C) 2013 Elsevier B.V. All rights reserved.