C_nS_m⁻ (n = 2–7; m = 1, 2) clusters were investigated by using photoelectron spectroscopy combined with density functional theory calculations. We found that the vertical detachment energies of both C_nS⁻ and C_nS₂⁻ (n = 2–7) clusters exhibit a strong odd–even alternation with an increasing number of carbon atoms: the VDEs of even-n clusters are higher than those of adjacent odd-n clusters. The most stable structures of the anionic and neutral C_nS (n = 2–7) clusters are linear with the S atom locating at one end of the carbon chain except that the structure of C₃S⁻ is slightly bent. The ground state isomers of the anionic and neutral C_nS₂ (n = 2–7) clusters are all linear structures with two S atoms locating at two ends of the carbon chain. The electron affinities of the neutral C_nS (n = 2, 4–7) and C_nS₂ (n = 2–7) clusters are determined based on the experimental adiabatic detachment energies of the corresponding anion species, because the most stable structures of the neutral clusters are similar to those of the corresponding anions.