Data are presented on the dissolution rates of films in a variety of acidic fluoride solutions. It is shown that the rate of dissolution is linearly dependent on the concentration of and HF in relatively dilute fluoride solutions. Both reactions have a similar temperature dependence characterized by an activation energy of 9.1 and 8.1 kcal/mole, respectively. The reaction with is about four to five times as fast as that with HF. Extrapolation to more concentrated solutions suggests that higher polymeric species of the type may also be active in the dissolution process. Raman data indicates that no single product species is formed although the product spectrum is consistent with the presence of some .