A Ce-TZP/platelike La(Co(Fe0.9Al0.1)(11))O-19 composite was synthesized in situ while sintering from a mixture of Ce-TZP, La(Fe0.9Al0.1)O-3, Fe2O3, Al2O3, and CoO powders. Platelike La(Co(Fe0.9Al0.1)(11))O-19 crystals were grown in a dense CeTZP matrix after sintering at temperatures of 1200 degrees-1350 degrees C. The temperature range for sintering Ce-TZP/La(Fe,Al)(12)O-19 composites was expanded widely by substituting Co2+ ions for Fe2+ ions in its structure. The highest value of the bending strength of the Ce-TZP/La(Co(Fe0.9Al0.1)(11))O-19 composites was 880 MPa, which was higher than that of the Ce-TZP/ La(Fe,Al)(12)O-19 composite (780 MPa) and Ce-TZP (513 MPa). The saturation magnetization of the Ce-TZP/ La(Co(Fe0.9Al0.1)(11))O-19 composite was a constant value of 7.7 emu/g after the composite was sintered at 1200 degrees-1350 degrees C.