Thermal stability of reactive magnetron sputter deposited oxygen vacancy stabilized cubic zirconia (OVSZ) thin films containing 16 and 3 at.% oxygen vacancies is reported. Temperature-resolved grazing incidence X-ray diffraction (TR-GIXRD) measurements (200-900 degrees C) in air and nitrogen atmosphere were performed. TR-GIXRD data show that the deposited films are stable up to 750 degrees C irrespective of the annealing atmosphere or the oxygen vacancy concentration. However, above 750 degrees C a fraction of zirconia transforms from cubic to monoclinic structure. This structural transition is explained by the compressive stresses, generated as a result of discrepancy in film-substrate thermal expansion coefficients. Thermal cycling of the deposited OVSZ thin films is also performed at 700 degrees C and show that films retain their initial cubic structure.