A new family of mixed-lanthanide cyano-bridged coordination polymers Ln(0.5)Ln(0.5)'(H2O)(5)[W(CN)(8)] (where Ln/Ln' = Eu3+/Tb3+, Eu3+/Gd3+, and Tb3+/Sm3+) containing two lanthanide and one transition metal ions were obtained and characterized by X-ray diffraction, photoluminescence spectroscopy, magnetic analyses, and theoretical computation. These compounds are isotypical and crystallize in the tetragonal system P4/nmm forming two-dimensional grid-like networks. They present a magnetic ordering at low temperature and display the red Eu3+ (D-5(0) -> F-7(0-4)) and green Tb3+ (D-5(4) -> F-7(6-2)) characteristic photoluminescence. The Tb0.5Eu0.5(H2O)(5)[W(CN)(8)] compound presents therefore green and red emission and shows Tb3+-to-Eu3+ energy transfer.