A new ultra-low-temperature firing microwave dielectric ceramic, Li2WO4 with the phenacite structure, was prepared via solid-state reaction method. The Li2WO4 ceramic can be well sintered at 640 degrees-660 degrees C, with a microwave relative permittivity similar to 5.5, a Qxf value about 62 000 GHz, and a negative temperature coefficient of -146 ppm/degrees C at 15.7 GHz. From an X-ray diffraction analysis, the Li2WO4 ceramic was found to be chemically compatible with both silver and aluminum powders at 640 degrees C. All the results indicate that the Li2WO4 ceramic is a promising candidate for ultra-low temperature cofired ceramic technology, especially for dielectric substrate application.