Cellulose benzylphosphonate (CBP) and its metal complexes with transition metals such as chromium, iron, copper and zinc have been synthesized as flame-retardant formulations on cellulose and when heated, these compounds give rise to high char yields. Enthalpy changes and char yields Suggest that such derivatisation may give rise to novel flame retardant treatments for cellulosic materials. The thermal degradation of cellulose, CBP and metal complexes of CBP has been studied by using TG and DSC from ambient temperature to 600 degrees C in static air. The FTIR spectra of chars of modified cellulose indicate that dehydration takes place and compounds containing C=O, C=C, P-O-P and P=O groups are formed.