Abstract: Energy-dispersive x-ray analysis with gas proportional detectors has been used widely in x-ray spectrochemical analysis. It was particularly useful in the detection of low-energy x-ray emission, before the commercial availability of the Blodgett-Langmuir pseudocrystals. With the development of solid-state x-ray detectors of high resolution, and improvement in associated electronics and computers, the interest in energy-dispersive x-ray analysis has increased enormously, to the point where it has replaced Bragg crystal diffraction spectrometry in many instances.