AbstractCoupled thermo-mechanical simulations were carried out to quantify permeability changes in representative coal measure strata surrounding an underground coal gasification (UCG) reactor. Comparing temperature-dependent and -independent rock properties applied in our simulations, notable differences in rock failure behavior, but only insignificant differences in spatial permeability development are observed. Hence, temperature-dependent parameters are required for simulations of the close reactor vicinity, while far-field models can be sufficiently determined by temperature-independent parameters. Considering our findings in the large-scale assessment of potential environmental impacts of UCG, representative coupled simulations based on complex thermo-hydro-mechanical and regional-scale models become computationally feasible.