The main concern of this paper is the development of a fully three dimensional viscoelastic model at finite strain to describe nonfactorizable behavior of rubber-like materials within the framework of rational thermodynamics and internal state variable approach such that the second law of thermody-namics in the form of Clausius-Duhem inequality is satisfied. The nonfactor-izable aspect of the behavior is introduced via a strain dependent relaxation times. The model is applied to describe the response of the isotropic Pip-kin multi-integral viscoelastic model and the BIIR material, several parameters involved are then identified using quasi-static and dynamic experiments thanks to a least-square minimization procedure performed with Matlab software. The proposed model is able to reproduce quasi-static experimental response and show an ability to predict the dynamic response of nonfactor-izable rubber-like materials in a wide range of strain.