The pure rotational spectrum of copper hydrosulfide, CuSH, has been recorded using millimeter/sub-millimeter direct absorption methods. Both copper isotopomers and their deuterated analogs were observed. The molecules were synthesized by the reaction of H2S or D2S with copper vapor in a do discharge. For all four isotopomers, multiple transitions were measured, each exhibiting extensive K-a ladder structure and signifying that CuSH is a near-prolate asymmetric top. Rotational parameters were determined for the four species, from which a structure has been derived. The Cu-S-H bond angle was found to be 93degrees, similar to other metal hydrosulfides and H2S, rather than CuOH. (C) 2004 Elsevier B.V. All rights reserved.