The paper is dedicated to the mechanical analysis of peel tests for a ductile film on an elastic substrate. This test is widely adopted to access the interface fracture energy. In the literature, the analytical analysis of the peel test is often based on the bending model to quantify the work done by bending plasticity within the film. Isotropic hardening is only considered. In the present work, a new contribution is proposed where the ductile film has an elastic-plastic behavior with combined kinematic-isotropic hardening. A semi-analytical expression for the work done by bending plasticity is obtained in the general case and a closed-form expression is found when only kinematic hardening is present. The validation of the theoretical work is established via finite element simulations of 90o peel test. Two model materials having the same uniaxial tensile response are considered: one presents isotropic hardening while the second only kinematic hardening. The comparison between them enables quantification of the role of kinematic hardening in the prediction of the interface fracture energy.