We present a study of the controlled synthesis and optical properties of single-crystals Gd(OH) 3 , GdOOH and Gd 2 O 3 nanorods. In this work, Gd(OH) 3 nanorods were synthesized by a simple and fast microwave-assisted hydrothermal method. This process combined with the thermal decomposition oxidation of Gd(OH) 3 nanorods as precursors enabled the preparation of single-crystalline GdOOH and Gd 2 O 3 structures with well-defined morphology at low temperatures. The crystal structure dependence on the optical properties was investigated. We observed a green shift effect on the photoluminescence (PL) emission spectra from Gd(OH) 3 to Gd 2 O 3 nanorods, which can be attributed to different types of surface defects, as well as intrinsic properties that contribute significantly to the modified PL behavior.