Two new U(VI) sulfates, [CH6N3](2)(NO3)(2)[(UO2)(SO4)(H2O)(2)]center dot H2O (1) and [C5H8N2](2)[(UO2)center dot (SO4)(2)] (2), were prepared by isothermal evaporation from aqueous solutions. Compound 1 crystallizes in the monoclinic system, space group P2(1)/n, a = 12.3824(7), b = 7.0329(4), c = 21.5362(12) , beta = 99.598(2)A degrees, and compound 2, in the triclinic system, space group P1I..., a = 7.0126(9), b = 10.3352(13), c = 13.8027(19) , alpha = 68.187(5)A degrees, beta = 78.940(5)A degrees, gamma = 71.339(3)A degrees. The crystal structure of the compounds was studied at 100 K. The structures were solved by direct methods and refined to R (1) = 0.059 and 0.032 for 1 and 2, respectively. The structure of 1 is based on electrically neutral [(UO2)(SO4)(H2O)(2)](0) chains between which protonated guanidine molecules, NO (3) (-) anions, and water molecules are located. In compound 2, protonated molecules of 4-aminopyridine bind [(UO2)(SO4)(2)](2-) chains in a three-dimensional structure. Specific crystal-chemical features of chain U(VI) compounds with tetrahedral oxoanions, derived from [(UO2)(TO4)(H2O) (n) ], T = S, Cr, Se, are considered.