The important advantage of energy-dispersive X-ray diffraction is the opportunity to obtain diffraction patterns without the use of any goniometer. Thus, a combination of small power X-ray tubes, appropriate X-ray optics and high energy-resolution detectors enables the construction of small and transportable measurement devices also for mobile use. Specimens of different size, shape, and geometry can be investigated. In this article, the application of energy-dispersive X-ray diffraction on polycrystalline materials is demonstrated and examples in the fields of micro system technologies, deposition techniques and quality control are presented.