<p>The present work focuses on the study of the interaction of rare-earth oxides (REOs: La₂O₃, CeO₂, Pr₆O₁₁, Nd₂O₃, Sm₂O₃, Eu₂O₃, Gd₂O₃, Tb₄O₇, Dy₂O₃, Ho₂O₃, Er₂O₃, Tm₂O₃, Yb₂O₃, Lu₂O₃, and Y₂O₃) with hydrogen using the H₂-TPR technique. The temperature windows for surface and bulk H₂-TPR peaks of all nanocrystalline rare-earth oxides were determined and discussed in detail. A comprehensive analysis of the reducibility of rare-earth oxides was also conducted. This analysis identifies the pathways and general trends of the reduction processes in nanocrystallites of all rare-earth oxides — key information for their use in a wide range of scientific applications, such as heterogeneous catalysis and luminescent materials.</p> Graphical Abstract <p></p>