Strain hardening is one of the key features of stainless steel for all structural applications. This property directly affects the definition of cross-sectional resistance, cross-section classification, ductility and energy dissipation. All these properties are fundamental in seismic design. Research related to seismic resistance at cross-section, member, connections and frame levels are necessary in order to assess its potential use in seismic areas as well as the performance of existing structures. In advanced numerical modeling, the cyclic properties of stainless steel must be implemented by means of a nonlinear isotropic/kinematic hardening model. For this purpose, test data and/or a multivariable mathematical definition are needed. In this paper, experimental results related to testing, calibration, comparison and analysis of nonlinear isotropic/kinematic models in stainless steel for seismic applications are presented.