Laser-ablated thorium atoms react with discharged sulfur vapor during co-condensation in excess argon at 7 K. The ThS fundamental is observed at 474.7 cm(-1), and the v, and v, modes for ThS2 are observed at 451.4 and 431.5 cm(-1), respectively, based on sulfur-34 substitution and infrared spectra of sulfur 32, 34 mixtures. Sulfur isotopic nu(3) vibrational frequencies for ThS2 indicate a 112 +/- 5degrees upper limit for the S-Th-S bond angle. Quasirelativistic DFT calculations performed on ThS and ThS2 find that ThS has the (1)Sigma(+) ground state, and ThS2 has the (1)A(1) ground state with a bond angle of 111.6degrees. Calculated vibrational frequencies are in excellent agreement with the observed values, and support this first identification of molecular thorium sulfides.