In recent studies, we have found that imidazolium magnetic ionic liquid based on tetrahaloferrate anions display very interesting magnetic and dynamic phenomena (highlight ILL 2016). Now, we want to extent the investigation to “Double Salt Magnetic Ionic Liquids” (DSMILs), which is an emerging field and, thereupon, more research is needed to understand these kind of systems in a fundamental way. For this issue, we have prepared a series of DSMIL solid-solutions of formula Dimim[Fe(ClxBrx-1)4], x ranging from 0.95 to 0.05. The accurate structural determination is mandatory to understand the unexpected magnetic behaviour as function of the Br- content. With this objective we kindly apply to 3 days on GEM to carry out high resolution neutron powder diffraction as function of the temperature.