Öz Potassium hexafluorotitanate was used for FR protection of wool (fibre and textile) in different conditions of treatment. Bleaching process was provided using of hydrogen peroxide and optical brightener bleaching system. The degree of FR protection was determined through the quantity of connected titanium in the wool. A modified procedure for the titanium determination in the wool using UV-vis spectrophotometry was developed. The connection between titanium content, bleaching and FR protection was established too