Isobaric volumetric heat capacities of aqueous solutions of K4Fe(CN)(6), K3Fe(CN)(6), K3Co(CN)(6), K2Ni(CN)(4), and KAg(CN)(2) have been measured at 298.15 K over the approximate concentration range 0.02 to 0.4 mol.kg(-1) using a Picker flow calorimeter. These data were combined with measured densities to calculate the corresponding apparent molar isobaric heat capacities, C-p phi. The values so obtained were fitted as a function of concentration using an extended Redlich-Rosenfeld-Meyer-type equation to provide the standard state (infinite dilution) quantities, C-p phi(o), for each salt. The C-p phi values for all the salts studied showed similar dependences on concentration, with a slight upward curvature at higher molalities, possibly due to anion aggregation. Values of C-p phi(o) for the aquated cyanometallate anions were estimated using the tetraphenylphosphonium tetraphenylborate extrathermodynamic assumption and were little affected by ion size but were strongly dependent on ionic charge, ranging from -191 J.K-1.mol(-1) for [Fe(CN)(6)](4-)(aq) to +178 J-K-1.mol(-1) for [Ag(CN)(2)](-)(aq). This indicates that the differences between the anions are mostly due to their effect on the surrounding water molecules.