The compounds A(1+x)M'3-2xBi7+xSe14 and A(1-x)M'3-xBi11+xSe20 (A = K, Rb, Cs; M' = Sri, Pb) were discovered from reactions involving A(2)Se, Bi2Se3, M', and Se at 760 degreesC. The single-crystal structures reveal that A(1+x)M'3-2xBi7+xSe14 are isostructural to K2.5Bi8.5Se14 whereas A(1-x)M'3-xBi11+xSe20 adopt a new structure type. Both compound types belong to the homologous series A(m)[M6Se8](m)[M5+nSe9+n] (M = di- and trivalent metal), whose characteristics are three-dimensional anionic frameworks with tunnels filled with alkali ions. The building units are derived from different sections of the NaCl lattice, perpendicular to the [111] (NaCl111-type) and [100] (NaCI100-type) directions, respectively, with dimensions and shapes defined by m and n. The structures of A(1+x)M'3-2xBi7+xSe14 (m = 2, n = 3) and A(1-x)M'3-xBi11+xSe20 (m = 1, n = 3) exhibit the same type of step-shaped NaCl111-type layer but differ in the size of the NaCl100-type unit. In both structures, the Bi and Sn (Pb) atoms are extensively disordered over the metal sites of the chalcogenide network. The physicochemical and charge transport properties of A(1+x)M'3-2xBi7+xSe14 and A(1-x)M'3-xBi11+xSe20 (A = K, Rb, Cs; M' = Sn, Pb) are reported.