[en] The interfacing of an energy dispersive x-ray spectrometer (EDS) to an HVEM has been suggested during the last few years as a means by which the mass sensitivity of x-ray analysis in a TEM can be increased. The prediction of higher sensitivity is related to the anisotropic distribution of continuum radiation generated by high energy electron excitation of a thin sample. Depending on the geometry, this can result in an increase in the measured peak-to-background (P/B) ratio of a characteristic line relative to excitation using lower energy electrons. In addition, the unique combination of a large pole piece gap and a wide variety of in-situ experimental stages makes an HVEM an ideal candidate for real-time microanalytical measurements during controlled dynamic events such as precipitation and fracture. A single-crystal specimen of β-NiAl of the 50-50 atomic percent composition was used to evaluate the performance of HVEM-based x-ray microanalysis. The instrument used for the experimental work was a Hitachi HU-1000 high-voltage transmission electron microscope operating at an accelerating voltage of 1 MV. X-ray measurements were made using a KEVEX Si(Li) solid-state x-ray detector with an active area of 10 mm² together with a model 5100 multichannel analyzer