High-quality, large single crystals of ternary bismuth molybdenum oxides have been prepared by the electrolysis of molten K2CO3-Bi2O3-MoO3 systems, in which K2CO3 is present as a fluxing medium. The unit-cell parameters and the compositions were determined by using X-ray diffraction and Fluorescent X-ray spectrometry, respectively. The empirical formula was refined to be Bi0.18MoOy. Thermoelectric power and resistivity measurements showed that the crystal exhibits a semiconducting behavior with p-type carriers and the thermal activation energy was estimated to be about 0.18 eV.