a b s t r a c t The growth of Pt particles in mesitylene-solvated metal atoms, obtained by metal vapour synthesis (MVS), has been followed at two temperatures (À40 and 25 °C) by NMR DOSY technique. The addition of 1,3-divinyltetramethyldisiloxane (DVS) at different time allows to quench the growth process and to make the resulting thermally stable solutions suitable for the evaluation of the Pt particles size at that moment. These solutions can be conveniently used to prepare supported Pt systems containing Pt parti-cles of tailored size.