A quantitative analysis of diffusion of iron in silicon dioxide is presented. A source of iron deposited on the surface of thermally oxidized silicon wafers was diffused at temperatures ranging from 700-1100 degrees C in an inert (nitrogen) ambient. The iron concentration in SiO2 and Si was measured using total reflection X-ray fluorescence, deep level transient spectroscopy, and surface photovoltage techniques. A two-boundary diffusion model was applied to the experimental data to determine the diffusivity and segregation coefficient of iron in SiO2. It is observed that iron diffusivity in SiO2 follows the Arrhenius relationship and has a thermal activation energy of 1.51 eV. Iron exhibits a strong tendency to segregate into silicon dioxide and has a value of k = 1.1 X 10(-7) at 1000 degrees C, where k = N-Si/N-oxide.