An energy-dispersive x-ray method for a rapid analysis of the broadening of diffraction lines in powder patterns has been developed. Experimental results are given for magnetite powders with sizes in the range 50–200 Å and compared with the results of standard angle-dispersive diffractometry and electron microscopy. The greatest advantages of the energy-dispersive method compared with the angle-dispersive method are the absence of the Kalpha doublet, the simultaneous recording of a large part of the diffraction pattern, the fast data accumulation, and the adaptability of the technique to in situ studies. The method should be of special advantage for the study of solid-state reactions and processes such as sintering. Journal of Applied Physics is copyrighted by The American Institute of Physics.