MO cubic phase containing gold nanoparticle (GNP) was prepared by hydrating MO melt with gold ionsolution to synthesize GNP of different sizes and shapes. A TEM microscopy and an elemental mappinganalysis disclosed that GNP could be formed within the cubic phase. GNP prepared in an aqueous solution(GNP(W)) exhibited its surface plasmon resonance (SPR) spectrum in the visible light region with thepeak around 528 nm and it was a sphere of which diameter was 10–30 nm. Besides a SPR spectrum inthe visible light region, GNP formed in the cubic phase (GNP(CP)) showed its SPR spectrum spanning fromthe far-red to the near-infrared region, indicating GNP(CP) was gold particles of different sizes andshapes. In fact, non-spherical particles, including tetrahedron, decahedron, and rod, were found on theTEM photo of GNP(CP) and were larger than GNP(W). Furthermore, GNP(CP) exhibited the inherent latticeconstant of gold, confirmed by a high-resolution TEM microscopy and an X-ray diffraction spectroscopy,indicating that various gold particles of different sizes and shapes could be formed in thecubic phase, maintaining its intrinsic crystalline structure.