Prussian White (PW) is a strategic cathode material for sodium-ion batteries, offering a high theoretical capacity and voltage. However, the crystalline structure and the electrochemical performance of PW strongly depend on the hydration level, which is difficult to control, leading to discrepancies in the results and interpretations presented in the literature. This work aims to provide a deeper insight into the dehydration process of PW materials and a better understanding of the impact of their fast rehydration, upon exposure to moisture, on their characterization. For this purpose, a Na