A new lithium iodide intercalation complex, Li0.3I1.0Bi2Sr1.4La0.1Ca1.5Cu2Oy, has been synthesized by applying a novel stepwise intercalation technique. According to X-ray diffraction analysis, lithium iodide species are stabilized between Bi2O2 double layers, leading to an increase of basal spacing of similar to3.4 Angstrom per host layer. X-ray photoelectron and X-ray absorption spectroscopic analyses reveal that there is little charge transfer between the intercalant lithium iodide layer and host lattice. In this context, the observed minute change of T-c upon Li-I intercalation can be regarded as evidence of the negligible contribution of interlayer coupling to superconductivity. On the other hand, ac impedance analysis demonstrates that the intercalation complex of lithium iodide species shows a Li+ ionic conductivity in the order of similar to 10(-6) Omega(-1) cm(-1) at a low temperature of <70degreesC. In combination with an excellent electronic conductivity of the host lattice, this material can be a new type of mixed Li+ ionic-electronic conductor. From the viewpoint of synthesis, the present compound is the first example of the stabilization of an alkali-metal halide in the two-dimensional metal oxide lattice.