Zirconium diboride was synthesized by pyrolysis of a novel polymeric precursor. Phase compositions and microstructures of the formed ceramic were characterized. It was found that a precursor with B/Zr molar ratio of 2 can completely transform into zirconium diboride by heating in an inert atmosphere with temperatures above 1500 degrees C. However, the initial formation temperature of zirconium diboride was as low as 1300 degrees C whereas zirconium oxide was also produced from the precursor at 1100 degrees C, the mixture was finally transformed into pure zirconium diboride at the elevated temperature. Zirconium diboride particles, dispersed relatively uniformly with characteristic dimension less than 100 similar to nm, were found to be formed following a liquid phase reaction mechanism.