Y(OH)3 is the main precursor material to inherit desirable morphologies for Y2O3. The Y(OH)3 and Y2O3 are an important substitution for luminescent matrix and useful in temperature sensing applications. Nanostructured and phase-pure Y2O3 is also used as an essential dispersoid for the oxide dispersion strengthened steels which are candidate materials for future fast breeder reactors. In the present work, the nanostructured Y(OH)3 is prepared indigenously by the microwave-hydrothermal route which is appropriate to provide-uniform heating to the material and the hydrothermal-pressure environment plays a major role in the growth kinetics of morphology. The synthesis was carried out at various microwave powers of 700 and 800 W to obtain the different morphologies of tubular and rod-like structures, respectively. The morphology is attributed to the influence of heat-rate on the variation in hydrothermal pressure governed by microwave power. The morphologies remain the same on calcination 800 °C. As-synthesized powder samples showed hexagonal structure whereas the cubic structure was observed for those calcined at 800 °C for both morphologies. The hydroxide vacancies lead to form a cubic structure that has a larger unit cell. The yttrium oxides showed lattice compaction for the rod-like structure but yttrium hydroxides did not depict any difference in the lattice for the tubular and rod-like morphologies. Likewise, Raman spectroscopy analysis confirmed the formation of hexagonal and cubic phases for the as-synthesized and calcined nanopowder samples, respectively.