Comparative studies on the intermetallic compound (IMC) formations of nano- and micro-size Sn with Ni and Cu in cold gas dynamic sprayed (CGDS, or Cold Spray) coatings were carried out. High purity pure nano (average 150 nm) and micro (under 45 μm) Sn were selected and prepared as raw materials mixture in order to be sprayed onto Ni and Cu plate-shape substrates. Nano particles of Sn were successfully coated under conventional coating parameters when they are mixed with microsize materials. And thermodynamic predictions regards to compound formation similarly worked out for both nano and micro Sn mixture. However, the kinetics of formation reaction were turned out to be different. In all case, nano particle showed more sluggish behavior. After post-annealing, microsize Sn formed larger amount of IMC with Ni than nanosize Sn although, owing to larger interfacial area, more intensive reactivities were expected. Also, there were significant differences in the size and distribution of eutectic pores as well.