Our recent study on the very first and high quality single crystal of UAu2Si2 revealed its interesting magnetic properties and complex magnetic phase diagram. We have determined a ground state magnetic structure below 19 K within our recent neutron diffraction experiment. The antiferromagnetic component of the structure is described by propagation vector (2/3,0,0) and magnetic moments are aligned along tetragonal c-axis. Ferromagnetic component was observed as a very weak magnetic signal on several nuclear reflections at 2 K, even though the FM component is traced in magnetization data already below 50K. We propose inelastic neutron scattering ToF experiment on IN4C spectrometer as a first step in inelastic study of this unique uranium based 1-2-2 compound. The mapping of magnetic excitations and phonons spectra in UAu2Si2 will allow us to continue with triple-axis studies on our high quality crystals in future. Proposed experiment would be performed within the stay of Ph.D student Michal Valiska (main proposer) at ILL (October 2017 - October 2018).