Abstract A new quaternary uranium(V) selenide, Ba8PdU2Se12(Se2)2, has been synthesized by reaction of elements at 1173 K. A single-crystal X-ray diffraction study shows that the compound crystallizes in a new structure type with two formula units in space group D2h12-Pnnm of the orthorhombic crystal system with cell constants of a=9.490(1), b=12.240(2), and c=13.780(3) Å. Its crystal structure consists of PdU2Se1212- units where U atoms are coordinated to six Se atoms in octahedral geometry and Pd atoms are coordinated to four Se atoms in square-planar geometry. These PdU2Se1212- units are separated by Ba to result in a salt-like crystal structure. This compound also contains Se22- dimers that are part of Ba coordination polyhedra. The formula charge balances as (Ba2+)8(Pd2+)(U5+)2(Se2-)12(Se22-)2. Theoretical calculations predict antiferromagnetic semiconducting behavior for this compound with a band gap of 1.6 eV. Temperature-dependent four-probe resistivity measurements on single crystal confirm the semiconducting nature with an activation energy of 0.18(1) eV. © 2015 Elsevier Inc.