The laser induced fluorescence spectra of the thiohydroxyl radical inert gas complexes, R.SH (R=Ne, Ar, and Kr) are reported. The spectra of numerous isotopomers involving S-32, S-34, Kr-84, Kr-86, H-1, and H-2 have been observed. By using isotopic shifts of the heavy atoms, and other observations, the overwhelming majority of the 60 observed vibronic transitions have been assigned as originating from the vibrationless level of the (X) over tilde(2) Pi state and terminating on specific vibrational levels (nu(SH), nu(b)(k), nu(s),) of the (A) over tilde(2) Sigma(+) state, where nominally nu, is the R-SH stretch, nu(SH) is the SH is the bending vibration. Vibrational frequencies, omega(e), and anharmonicities, omega(e)x(e), for many of the modes are obtained, as well as dissociation energies (assuming a simple model) for both the (A) over tilde and (X) over tilde states of the R.SH complexes. (C) 1997 American Institute of Physics.