Abstract: The thermal decomposition processes and hydrogenation reactions of K₂Co[Fe(CN)₆]•H₂O and Co₃[Fe(CN)₆]•7H₂O in hydrogen were studied by GC to discern the gas products and by Mossbauer spectroscopy, IR and XRD to determine the struc-ture of the solid products. Their decomposition processes may be divided into three steps:(1) dehydration, (2) reduction of Fe (Ⅲ) to Fe(Ⅱ), and (3) rupture of the triple bond of C≡N^- by hydrogenation to evolev NH₃ and CH₄. Iron-Cobalt alloy was formed at the final step of decomposition. K₂Co[Fe(CN)₆)•H₂O and Co₃[Fe(CN)₆]•7H₂O may be considered as a multibond activation model of bimetal coordination, since CN^- acts as a typical ambident ligand in it. The activation of CN^- triple bond has been discussed in terms of hydrogenation reaction.