In several types of applications of microradiography, particularly for histochemical and microchemical analysis by x‐ray absorption spectroscopy, it is desirable to use monochromatic radiation of a wavelength selected specifically with reference to an absorption edge of the element of interest. An x‐ray tube having as its target a material whoseK&agr;characteristic wavelength is suitable is the most usual source of monochromatic x‐radiation. In many cases, however, an otherwise desirable target is physically unsuitable for use as a target inside a vacuum tube. Hence, the possibility of producing fluorescent characteristic radiation with intensities sufficient for microradiography becomes of interest. The very high intensity of the primary x‐ray beam made available by the newly developed beryllium‐window x‐ray tubes suggests new possibilities for the excitation of fluorescent radiation.This paper reports the results of exploratory work attempting to establish the factors governing the intensity and degree of monochromaticity of fluorescent x‐radiation. Several materials, ranging from titanium (atomic number 22) to molybdenum (42) were studied comparatively, with exciting radiations of various characteristics; titanium was studied in greater detail. It is concluded that a considerably higher degree of monochromaticity is obtainable by this method than by direct bombardment and that intensities useful for some aspects by microradiography are obtainable.