The set-gel method was applied to the preparation of zircon, ZrSiO4 powders. The addition of lithium ions to the ZrO2. SiO2 gels was found to be very effective to produce zircon at temperatures as low as 800-900 degrees C. The zircon formation process in the gels was followed by using X-ray diffraction and i.r. analysis methods. A possible mineralizing mechanism of lithium ions, which is essentially different from the previous ones for the solid-state reaction, was proposed. Namely, the formation of orthosilicate such as Li4SiO4 as an intermediate compound was considered to trigger the zircon formation at low heat-treatment temperatures.