In this study, micrometric uranium oxide particles produced by hydrothermal method were characterized. The applicability of the produced particles as reference materials for particle analysis, especially for mass spectrometry was evaluated in terms of morphology, size, isotope ratios, storage stability, and uranium yield. In addition, we compared the particles before and after heat treatment in air with the Nuclear Signatures Inter-laboratory Measurement Evaluation Programme-9 (NUSIMEP-9) particles. The results showed that the particles produced by hydrothermal method could meet the uniformity and stability of reference materials required for particle analysis.