On heating, milling and sonication, cadmium ferricyanide decomposes and reduces to cadmium ferrocyanide. Two compositions were studied, pure cadmium ferricyanide and mixed potassium-cadmium ferricyanide. The role of reducing agent is played by the CN - anions liberated during the decomposition process. The solid decomposition product is composed by several phases of cadmium ferrocyanide, an Fe 3 + phase and also potassium ferrocyanide in the case of the mixed complex salt. The decomposition process was monitored using DTA, XRD, IR and Mossbauer techniques. No occurrence of linkage isomerization in cadmium ferricyanide was detected.