By combining molecular beam photodissociation and photoionization measurements with ab initio Gaussian-2 (G2) calculations on the CH3S2 and CH3S2+ systems, we have shown that CH3SS is the dominant isomer formed in the photodissociation process, CH3SSCH3+hv(193 nm) -->CH3S2+CH3. The experimental ionization energy for CH3SS (8.97+/-0.02 eV) and the heat of formation at 0 K for CH3SS+ (217.7+/-1.2 kcal/mol) are in excellent agreement with the G2 results. The photoionization efficiency spectrum observed for CH3SS is also consistent with the theoretical prediction that the Franck-Condon factor for the photoionization process, CH3SS+hv -->CH3SS+ +e-, is not favorable. Based on the statistical modeling of experimental rates obtained previously for HS loss in the unimolecular decomposition of CH3SSCH3+ and the comparison with G2 ab initio predictions, we conclude that CH2SSH+ is most likely the isomer structure formed near the experimental appearance energy (11.07 eV) observed for the photodissociative ionization process, CH3SSCH3+hv-->CH3S2+CH3+e-.