The Institut de Radioprotection et de Suret ˆ e Nucl ´ eaire (IRSN) carried out time-of-flight experiments ´ for light water at several temperatures and pressures aiming at developing new evaluations of thermal scattering law based on experimental data. Measurement of dynamic structure factor S(q, ω) for light water has been carried out at the Institut Laue-Langevin (ILL), Grenoble. The S(q, ω) has then been transformed to density of states/frequency spectrum and utilized to generate the thermal scattering law using the LEAPR module of the NJOY nuclear data processing code. The thermal scattering law has been evaluated for the experimental temperatures varying from room temperature up to 500K. The impact of the newly developed thermal scattering law data on criticality safety benchmarks is investigated and compared with the existing thermal scattering law evaluations available in the JEFF-3.3 and ENDF/B-VIII.0 nuclear data library