To characterize the kinetics of rafting, mechanical tests and microstructural investigations have been performed for the single crystal superalloy CMSX-4. The kinetics of microstructural degradation under constant load have been investigated in the temperature range 850-1100°C and for a large range of stress levels. An analytical model of the rafting kinetics has been proposed to represent the influence of temperature, stress and time on the microstructure degradation. To predict the degradation effect of rafting on the mechanical behavior of single crystal superalloys and its kinetics during complex loadings, a specific viscoplastic constitutive model has been developed. The degree of rafting is incorporated in the model via the γ-channels width, which determines the Orowan stress. The rafting kinetics are assumed to be driven by the reduction of internal stresses represented by the macroscopic back-stress. The model has been calibrated for the temperatures 950°C and 1050°C. Several validation tests have been simulated.