Real ferromagnetic materials exhibit complex hysteresis effects, which require memory dependent constitutive mapping between the magnetic field H and the flux density B for solving low-frequency Maxwell’s equations. Operator-based phenomenological approaches, such as the Prandtl-Ishlinskii (PI) model, are widely used for this purpose. In these models, the constitutive relation is typically expressed through a vector-valued, rate independent operator H = V[B]. To effectively integrate such models within a Finite Element (FE) framework, it is necessary to identify beforehand the model's parameters for a given material, such that the model's response provides a better fit to the hysteretic measurements. The aim of this thesis is to investigate and develop a new parametrization procedure, particularly for the generalized stop-type PI models, that improves the accuracy and fittings of the minor and major hysteresis loops. This parametrization, based on the generalized stop-type PI models is carried out for the existing nonlinear stop-type and a newly formulated linear stop-type cases. Initial focus could be given to the parametrization of isotropic materials and further extension to 2d/3d anisotropic cases.