Abstract: The present invention concerns a method and implementing equipment for detecting at least one object containing a specified material and hidden from view. The method comprising stages of object irradiation by a collimated x-ray beam (21) with an energy range containing a photo-ionization threshold, of detection of the beam having passed through said object (24), is characterized in that furthermore a continuous function representing the attenuation or transmission of the x-rays expressed in terms of energy is determined and a search is made near the energy corresponding to said photo-ionization threshold along the curve representing said continuous function of attenuation or transmission of an inflection point characteristic of the presence of said material. Illustratively this invention is applicable to airport luggage inspection.