A highly thermally stable, polar MOF built from the rigid ligand benzene-1,4-dicarboxylate and the main-group metal ion Sr(2+) shows ferroelectricity. With the ultimate goal of making components for use in devices, the fabrication of MOF thin films on Al(2)O(3), SrAl(2)O(4), and Al foil substrates using the in situ solvothermal method was explored. The mechanism of macroscopic polarization reversals in the ferroelectric MOF under an ac electric field and the dependence of the morphology of the MOF thin film on the nature of the substrate surface are discussed.