Sputtered platinum nanocluster growth on previously plasma enhanced chemical vapor deposition - PECVD - grown vertically aligned carbon nano ber arrays is presented. Experimental cluster size distribution is shown to decrease from the CNF top to bottom, as observed by transmission electron microscopy. Molecular Dynamics simulations are carried out for understanding early stages of Pt growth on model CNF arrays. Especially, sticking coefficients, concentration profi les along CNF wall, cluster size distributions are calculated. Simulated cluster size distribution are consistent with experimental fi nding. Sticking coeffi cient decreases against deposition time. The shape of the sticking curve reflects the nanocluster growth process.