We synthesized two one-dimensional compounds K2MSbS3(SH) (M = Zn, Cd) at 473 K, using thiourea as reactive flux. The compounds crystallize in the triclinic space group P (1) over bar. Their structures feature one-dimensional (1)(infinity)[M2Sb2S6(SH2)](4-) double chains along the crystallographic a axis. The (1)(infinity)[M2Sb2S6(SH2)](4-) double chains are composed of [M2Sb2S8(SH)(2)](8-) eight-membered rings. Similar band gaps of the two compounds, E-g = 2.75 eV for K2ZnSbS3(SH) and E-g = 171 eV for K2CdSbS3(SH), were obtained from optical absorption measurements, which are consistent with theoretical calculations. The analysis of density of states indicates that the valence band maximum and conduction band minimum consist mainly of S-3p orbitals and Sb-5p orbitals, respectively.