Recently, our group reported, for the first time, the in situ nucleation and growth of Ag NPs on the surface of silver compounds, Ag2WO4 and Ag2MoO4 driven by an accelerated electron beam under high vacuum (from an electronic microscope) [1-3]. This phenomenon generates new material, with possibilities of many applications, as well as, photocatalyst, sensor and bactericide [4, 5]. Since the growth of Ag NPs on the surface can change the properties of the material, a complete study about these are necessary. Our aim in here is study the properties of these material at low temperature using neutron diffraction, since this technic is more accurate than the X-ray diffraction, so we have more elements to understand the materials properties irradiated and non-irradiated, with neutron beam.