Nanosized beta carbon nitride (beta-C3N4) (a = 6.4017 Angstrom, c = 2.4041 Angstrom) has been synthesized by mechanochemical processing. The developed low-cost synthetic method facilitates the effective synthesis of nanosized beta-C3N4 powders. The graphite powders were first milled in a ball to a nanoscale state, then the nanosized graphite powders were milled in the presence of the NH3 gas. After thermal annealing in the presence of N-2 gas flow, the beta-C3N4 is relatively stable, the shape of the beta-C3N4 changes from flake-like to sphere-like. The rigorously acid-washed nanosized beta-C3N4 crystal was characterized by X-ray diffraction, Fourier transformation infrared spectroscopy, Raman spectra, transmission electron microscopy and parallel recording electron energy-loss spectroscope, X-ray photoelectron spectroscopy and EDX. (C) 2003 Published by Elsevier Science B.V.