Boron-undoped and -doped europium-bismuth oxide nanocomposites were synthesized by the polymeric precursor technique. The solutions were calcined and sintered to prepare nanocomposite powders. The nanocomposites were characterized by the Fourier transform infrared spectroscopy, x-ray diffraction, scanning electron microscope, and Brauner-Emmett-Teller techniques. According to Fourier transform infrared spectroscopy results, the shape, the range, and the intensity of the peaks for the calcined and sintered samples changed with the addition of boron content. Furthermore, the reaction path, resulting crystal size, and crystal morphology were all altered by boron additions. A decrease in porosity, brought about by boron additions, also altered the N-2 absorption/desorption characteristics.