Three new palladium compounds, PdSeO3, PdSe2O5, and Na2Pd(SeO4)(2), containing selenium oxoanions of both Se(IV) and Se(VI) have been prepared under mild hydrothermal conditions. PdSe2O5 and Na2Pd(SeO4)(2) both possess one-dimensional structures. Within the structure of PdSe2O5, [PdO4] square planar building blocks are joined together through diselenite, Se2O52-, anions, and form a zigzag chain along the c axis. In Na2Pd(SeO4)(2), [PdO4] units are connected by two selenate, SeO42-, anions, and extend along the a axis to form a [Pd(SeO4)(2)](2-) chain. Na+ cations reside in the space between the [Pd(SeO4)(2)](2-) chains and act as counter cations. Unlike above two compounds, PdSeO3 exhibits a layered structure. In the structure of PdSeO3, [PdO4] units are connected to each other by corner-sharing and form a zigzag chain along the b axis. The chains are further joined together by tridentate selenite, SeO32-, anions to form layers in the [ab] plane that stack along the c axis. Crystallographic data: (193 K; Mo K alpha, lambda = 0.71073 A): PdSeO3, monoclinic, space group P2(1)/m, a = 3.8884(5) A, b = 6.4170(8) A, c = 6.1051(7) A, beta = 96.413(2)degrees, V = 151.38(3) A(3), Z = 2; PdSe2O5, monoclinic, space group C2/c, a = 12.198(2) A, b = 5.5500(8) A, c = 7.200(1) A, beta = 107.900(2)degrees, V = 463.8(1) A(3), Z = 4; Na2Pd(SeO4)(2), triclinic, space group P $$($) over bar, a = 4.9349(11) A, b = 5.9981(13) A, c = 7.1512 (15) A, alpha = 73.894(4)degrees, beta = 86.124(4)degrees, gamma = 70.834(4)degrees, V = 192.03(7) A(3), Z = 1.