The material creep properties are described by complex probabilistic exponential model with damage developed by Bina et al [1]. The model contains a total of 18 constants and describes the development of deformation in the primary, secondary, and tertiary stages of material creep. The dependence of elastic moduli and creep parameters on temperature is included. The key variable is damage changing in the interval (0,1), i.e., from the beginning of the process to local fracture. In the early 1990s, the model was generalized for 3D and extended with extremely robust explicit integration, which is fully automatically controlled by a posteriori error estimation [2]. The algorithm was implemented in the finite element code PMD (Package for Machine Design) [3] and Abaqus for the solution of complex engineering problems. This work was focused on the development of a calibration procedure for the parameters of a complex creep model. The proposed calibration method is based on the work of the model's author, complemented by a new alternative procedure for parameter determination based on nonlinear regression analysis. The calibration procedure was programmed in the MATLAB environment and applied to determine the parameters of a complex creep model for heat-resistant steel. [1] V. Bína, J. Hakl. Probabilistic approach to description of the creep strain characteristic and prediction for long life-time. In Proc. Conf. Materials for Advanced Power Engineering, D. Coustouradis et al.(eds).Kluwer Academic Publishers, Dordrecht (Boston), 601-610, 1994. [2] J. Plešek, J. Korouš. Explicit integration method with time step control for viscoplasticity and creep. Advances in Engineering Software, 33: 621-630, 2002. [3] PMD version f77.11, VAMET/Institute of Thermomechanics, 2013.