Directionally solidified composites of the pseudobinary system ZrO2-Fe-3 O-4 were grown by the floating zone method at solidification rates from 2.5 to 40 mm/h in an air atmosphere. The composite had a fibrous microstructure which contained ZrO2 fibers in a magnetite matrix. Monoclinic ZrO2 fibers were obtained by dissolving the matrix in a concentrated hydrochloric acid. The diameters of the fibers were about 0.5-2 mu m, and their lengths were up to 100 mu m.