In this contribution an experimental procedure to characterize an epoxy-based adhesive is presented. Displacement controlled tensile tests at different rates of loading, relaxation experiments and deformation controlled loading and unloading processes with intermediate relaxations are used to classify the nonlinear, inelastic mechanical behavior. Based on these results parameter identification for a continuum based material model has been carried out. The proposed material model is a viscoelastic constitutive law based on an overstress formulation.