The synthesis and characterization of the neutral uranylisocyanate UO2(NCO)(2)(OP(NMe2)(3))(2) [crystal data: monoclinic, P2(1)/c, a = 8.512(2) Angstrom, b = 10.931(2) Angstrom, c = 14.329(3) Angstrom, beta = 103.923(3)degrees, V = 1294.0(4) Angstrom3, Z = 2] and isocyanato uranate (Et4N)(6)[(UO2)(2)(NCO)(5)O](2)(.) 2CH(3)CN(.)H(2)O [crystal data: monoclinic, P2(1)/c, a 17.2787(2) Angstrom, b = 15.560(l) Angstrom, c = 32.7619(4) Angstrom, beta = 94.0849(5)degrees, V = 8786.5(2) Angstrom3, Z = 4] are reported. Not only are these compounds the first unambiguously characterized uranium isocyanates regardless of the oxidation state for uranium, but they are also the first structurally characterized actinide isocyanates. Both compounds show coordination of the OCN moiety through nitrogen to uranium and were characterized using IR and H-1, C-13, N-14, and P-31 NMR spectroscopy and X-ray diffraction.