Five quinternary selenides, Sr2.63Y0.37Ge 0.63Sb2.37Se8 (I), Sr2.63La 0.37Ge0.63Sb2.37Se8 (II), Sr 2.71La0.29Sn0.77Bi2.23Se 8 (III), Ba2.67La0.33Sn0.67Sb 2.33Se8 (IV), and Ba2.67La 0.33Sn0.67Bi2.33Se8 (V), were synthesized by solid-state reaction in fused silica tubes. These compounds are isostructural and crystallize in the Sr3GeSb2Se 8 structural-type, which belongs to the orthorhombic space group Pnma (no. 62). Three structural units, [MSe3]1, [M4 Se10]1 (M=Tt, Pn) and M′ (M′=groups II and III element), comprise the entire one-dimensional structure, separated by M′. Measurements of electronic resistivity and diffused reflectance suggest that IV and V have semiconducting properties. Electronic structure calculations confirm the site preferences of Sr/La element discovered by crystal structure refinement.