[en] X-ray fluorescence (XRF) is a nondestructive, multielemental, fast and cost-effective analysis technique. It can be applied in a nonvacuum environment directly on the samples without any preparation. As archaeological and historical objects are often unique and may not be easily movable, a mobile XRF detector system allowing in situ analysis is ideally suited for archaeometric applications. A mobile system was designed and built at the IPNAS laboratory to provide such analyses. The system includes an industrial grade x-ray generator which supplies the primary x-ray beam, an air-cooled silicon rift Detector detector (SDD) with a 5-mm(2) active area. The data acquisition system measures the energy and the intensity of the secondary fluorescence x-rays. The detector signal is amplified and analyzed by a multichannel recorder coupled to a microcomputer running JavaSpectre which visualizes and analyzes spectra obtained from the detector. The detection head, containing the detector, the x-ray tube and its power supply, are fixed on a movable platform allowing independent vertical and horizontal movement. All displacements are controlled by a hand-held personal digital assistant (PDA) (Palm) which exchanges data with microcontrollers embedded in the system providing a very precise positioning of the detector over a surface of many square meters. This system control, as well as a typical application of this XRF spectrometer for analyzing pigment composition of a wall painting, will be described. Copyright (C) 2008 John Wiley & Sons, Ltd.