In(OH)3 and In2O3 nanocrystals of rectangular shape and incorporating Au were synthesized with a hydrothermal process and thermal decomposition. Powder X-ray diffraction, electron microscopy (SEM, TEM), and energy-dispersive spectroscopy studies reveal that elemental Au nanoparticles are dispersed on the surface of In(OH)3 rectangular nanocrystals and incorporated into In2O3 nanoporous particles. UV-vis spectral measurements reveal a surface-enchanced plasma band near λ ~532 nm for both Au-incorporating nanomaterials. The BET surface areas of Au-incorporating In(OH)3 and In2O3 are 26.2 and 35.5 m2/g, respectively. The incorporation of elemental Au in In(OH)3 and In2O3 nanomaterials is attractive for sensor, catalyst and solar-cell applications.