The transition of disc-like chromium hydroxide nanomaterials to chromium oxide nanomaterials has been studied by hot-stage Raman spectroscopy. The structure and morphology of α-CrO(OH) synthesised using hydrothermal treatment were confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The Raman spectrum of α-CrO(OH) is characterised by two intense bands at 823 and 630 cm−1 attributed to ν1 CrIIIO symmetric stretching mode and the band at 1179 cm−1 attributed to CrIIIOH δ deformation modes. No bands are observed above 3000 cm−1. The absence of characteristic OH stretching vibrations may be due to short hydrogen bonds in the α-CrO(OH) structure. Upon thermal treatment of α-CrO(OH), new Raman bands are observed at 599, 542, 513, 396, 344 and 304 cm−1, which are attributed to Cr2O3. This hot-stage Raman study shows that the transition of α-CrO(OH) to Cr2O3 occurs before 350 °C. Copyright © 2010 John Wiley & Sons, Ltd.