The mechanochemical transformations of Ag, Hg and Pb cyano complexes (ferroand ferricyanides, cobalticyanides, nitroprussides, hexacyanoplatinates and tetracyanonickellates) during milling and pressing with K B r have been studied using IR, XFUI and Mossbauer techniques as sensors. Exchange of K+ and the heavy metal cations is observed in all cases.