The use of a laser ablation cluster source made it recently possible to study Ostwald ripening of supported Pt nanoclusters with atomic control of the initial size distributions, such as Pt-68 or Pt-22 + Pt-68 (K. Wettergren et al., Nano Lett. (2014)). Monodispersed clusters were found to be more stable compared to the bimodal ones and to those with wide polydisperse initial size distribution. To clarify the results of the experiments, we present here the corresponding kinetic Monte Carlo simulations of Ostwald ripening with emphasis on the role of the initial size distribution with control at the atomic level. (C) 2015 Elsevier B.V. All rights reserved.