The microwave spectrum of the water-carbon disulfide complex has been observed with a pulsed-beam, Fabry-Perot cavity, Fourier transform microwave spectrometer. In addition to the normal isotopic form, we have also observed the spectrum of (\mathrm{H}{2} \mathrm{O}-{ }^{34} \mathrm{SCS}, \mathrm{HDO}-\mathrm{CS}{2}), HDO({ }^{34} \mathrm{SCS}, \mathrm{D}{2} \mathrm{O}-\mathrm{CS}{2}), and (\mathrm{D}{2} \mathrm{O}-{ }^{34} \mathrm{SCS}). The rotational constants are (B=1030.1109(6) \mathrm{MHz}) and (C) (=1026.2912(6) \mathrm{MHz}) for (\mathrm{H}{2} \mathrm{O}-\mathrm{CS}{2} ; B=1028.4595(8) \mathrm{MHz}) and (C=1024.6511(8) \mathrm{MHz}) for (\mathrm{H}{2} \mathrm{O}-\mathrm{SC}^{34} \mathrm{~S} ;(B+C) / 2=990.5359(8) \mathrm{MHz}) for (\mathrm{HDO}-\mathrm{CS}{2} ;(B+C) / 2=989.2168(2) \mathrm{MHz}) for (\mathrm{HDO}-{ }^{34} \mathrm{SCS} ; B=959.3024(8) \mathrm{MHz}) and (C=953.5587(8) \mathrm{MHz}) for (\mathrm{D}{2} \mathrm{O}-\mathrm{CS}{2} ;) and (B=) (958.2422(6) \mathrm{MHz}) and (C=952.5114(6) \mathrm{MHz}) for (\mathrm{D}{2} \mathrm{O}-{ }^{34} \mathrm{SCS}), respectively, with uncertainties of two standard deviations shown in parentheses. Stark effect measurements for (\mathrm{H}{2} \mathrm{O}-\mathrm{CS}{2}) give a dipole moment of (6.931(34) \times 10^{-30} \mathrm{Cm}[2.078(10) \mathrm{D}]). The most probable structure of (\mathrm{H}{2} \mathrm{O}-) (\mathrm{CS}{2}) is (C_{2 v}) planar with the sulfur atom of carbon disulfide bonded to the oxygen atom of water. The oxygen-sulfur van der Waals bond length is calculated to be (3.20 \AA). The structure of (\mathrm{H}{2} \mathrm{O}-) SCS is unusual because the structure of the isoelectronic molecule, (\mathrm{H}{2} \mathrm{O}-\mathrm{CO}{2}), is known to be (\mathrm{T}) shaped with an (\mathrm{O}-\mathrm{C}) van der Waals bond, i.e., the oxygen atom of water bonded to the carbon atom of (\mathrm{CO}{2}). 1993 Academic Press, Inc.