Vanadium specimens have been prepared and imaged for the first time in the field ion microscope. The composition of oxide films formed on vanadium at temperatures between 290 and 473 K has been determined by atom probe microanalysis. It is shown that the outer oxide film has a composition close to V₂O₃ in this temperature range, and that an intermediate layer of suboxide of composition approximately V₉O forms between the outer oxide and the metallic substrate. Appreciable solubility of oxygen in the vanadium metal matrix is also observed.