Raman spectroscopic and 35Cl-NMR scans of Hydro-Xan®, a preparation containing the biocatalytically effective Tetrachlorinedecaoxide anion (TCDO), are described. The spectroscopic analyses showed that HydroXan® does not contain chlorite initially used in the preparation anymore. Furthermore, a structure of four equal chlorate-like ClO3-groups was indicated for TCDO by the scans. Such a structure is supported by the long-term stability of HydroXan® found at tests over 267 days.