White fuming nitric acid (WFNA) is a storable liquid oxidizer used with kerosene and hydrazine rocket fuel. It consists of nearly pure nitric acid (HNO3). WFNA is commonly specified as containing no more than 2% water and less than 0.5% dissolved nitrogen dioxide or dinitrogen tetroxide.
WFNA was sometimes used with an inhibitor compound to reduce corrosiveness, often hydrogen fluoride. Without inhibitors, WFNA will corrode nearly all structural metals. Inhibited WFNA is often called IWFNA. The hydrogen fluoride addition causes formation of protective layer of fluoride on the metal surfaces.