Recently, it was reported that the formation of Ag-0 by ketyl radical and the growth of initial Ag clusters in toluene [5] follows the different path as compared to that in aqueous solution. Herein, we have shown that the reactivity of ketyl radical towards Ag+ depends on the experimental conditions under high dose rate in polar media. Further studies suggest that the interaction of tryptophan with silver clusters also depends on the medium. (C) 2012 Elsevier B. V. All rights reserved.