We report luminescence and absorption studies for the quasi-one-dimensional systems, Ba(Pt, Pd)(CN)4. nH2O and Ba(Pt, Ni)(CN)4. nH2O, to identify the delocalized and localized electronic states. For Ba(Pt, Pd) (CN)4. nH2O crystals a luminescence peak at 4200 A is interpreted as emission from a Pt-Pd delocalized excited electronic state; also, emission peaks appear which are assigned to Pt(CN)4 -2 clusters. Lifetime versus temperature data for Ba(Pt, Pd)(CN)4. nH2O and BaPt(CN)4. 4H2O have been analysed by a three level model to give relative energies and rate constants for the emitting states of these two systems. For the Ba(Pt x Ni1-x ) (CN)4. nH2O system (x = 0 to 1) pellet absorption measurements as a function of x allow us to determine the change in the energy of the electronic states versus x. These results have been correlated with extended Huckel MO calculations. Finally, a comparison is made between the mixed metal quasione-dimensional systems and ternary semiconductor alloys.