The theoretical basics for the simulation of the inert gas influence on explosion limits of fuel gas/air-gas mixtures of the halfempirical simulation model EPSIM are detailed described. Through modifications of this model it is possible to simulate the inert gas and fuel gas influence on the pressure limits of stability of C2H2 at different initial temperatures for the first time. The simulation model is based on the conservation equations for the minority species and energy without consideration of heat losses by radiation for the propagation of an one dimensional, stationary, premixed, laminar flame. The necessary border criterion for an explosion limit or a stability limit is a certain flame temperature, which is than constantly assumed about the further process of the limit curve. This flame temperature is calculated using measured stability limits or explosion limits. For the determination of the reaction enthalpy of the system the equilibrium constants of the formulated gross reactions are iterative calculated. Apart from homogeneous also heterogeneous gross reactions, especially the important decomposition reaction with the formation of elementary carbon, are considered for the first time. The simulation results are validated by pressure limits of stability determined experimentally at several initial temperatures for C2H2, C2H4 and C2H2/N2-, C2H2/CO2-, C2H2/H2-, C2H2/NH3-, C2H2/C2H4-gas mixtures. By visualization of a C2H2-decomposition with high speed videotakes and from the simultaneously measured pressure/time-curves the detailed form of the pressure/time-curve can be explained physically for the first time. The connection of stability limits and explosion limits is represented by the example of the ternary gas system C2H4/N2/Luft at an initial pressure of 100 bar and different initial temperatures. The inert gas influence on the explosion limits of C2H4/air-systems is also simulated.