Abstract: The present paper is concerned with the modeling of superplasticity phenomenon in metallic materials using a continuum damage theory. The goal is to propose a one-dimensional phenomenological damage model, as simple as possible, able to perform a mathematically correct and physically realistic description of plastic deformations, strain hardening, strain softening, strain rate sensitivity and damage (nucleation and growth of voids) observed in tensile tests performed at different strain rates. Only two tensile tests at different controlled strain rates are necessary to obtain all the material parameters that appear in the theory. Examples concerning the modeling of tensile tests of a magnesium alloy at different strain rates are presented and analyzed. The results obtained show a very good agreement between experimental results and model prevision.