Fundamental study down to the atomic level is crucial for improving our understanding of catalysts and enhancing our ability for their rational design. The present project deals with exploring advanced TEM techniques such as aberration corrected microscop y and environmental TEM for imaging of composition and bonding. Elemental and valence sensitive imaging of Co nanoparticles and Pt based core-shell structured nanoparticles will be obtained by STEM combined electron diffraction and electron energy loss sp ectroscopy. The strain of the nanoparticles will be studied as a function of particle size and different supports in terms of catalytic performance in different reactions. The thickness and uniformity of the shell of core-shell structured nanoparticles wi ll be studied by atomic imaging. The interface between core and shell layers will be studied by aberration corrected microscopy. The project will enhance the cooperation with world leading groups at DTU and Lehigh University.