Understanding the human body response during impact has become a primary concern, especially in the field of ballistic impacts. Among various materials employed as human body substitutes, synthetic gel named SEBS is used in the present study. Mechanical characterization from quasi-static to very high strain rates are performed allowing the constitutive modeling of the gel material and its implementation in an explicit finite element code. Tensile testing are completed using appropriate tensile fixtures and specific strain measurement and point out a hyperelastic behavior (strain over 300%) with strain rate sensitivity. Compression tests are performed from static strain rates to dynamic strain rates using for very high strain rates polymeric split Hopkinson bars and high-speed imaging. Mooney-Rivlin hyperelastic material model with specific strain rate dependence is implemented using optimization process by inverse method of dynamic compression testing results for material parameters identification. The material law is employed during modeling of direct impact of less lethal kinetic energy projectiles over various velocities and gives satisfactory results compared to the experimental impact analysis