Epitaxial superconducting Bi2Sr2CaCu2Ox(BSCCO) thin films have been formed by solid phase epitaxy from amorphous films deposited by metallorganic chemical vapor deposition. (100) MgO and LaAlO3single crystals were used as the substrates. After high‐temperature annealing in flowing oxygen, the films consist predominantly of the BSCCO (2212) phase and are epitaxial to the LaAlO3with thecaxis perpendicular to the substrate surface. The epitaxial structure of the films is confirmed by x‐ray diffraction measurements including &thgr;/2&thgr; and in‐plane &Fgr; scans as well as by cross‐sectional high‐resolution transmission electron microscopy. Four‐probe resistivity measurements show that the critical temperature of the film on LaAlO3is 78 K. The critical current density of the epitaxial layer was one order of magnitude greater than that of textured films on MgO.