A superlastic material, aluminum - lithium alloy 8090, were examined with uniaxial tensile test to investigate its thermomechanical behavior. The tests were carried out at the strain-rates ranging from 210-4 to 110-2 and at the temperatures from 48 0 to 540. The experiments produced force-displacement curves which converted to stress-strain curves. From the curves, several important superplastic factor such as strain-rate sensitivity, optimum strain-rate and strength coefficient were obtained.