This thesis deals with thermodynamic stability of thaumasite in dependence on selected external parameters. It focuses on optimizing preparation by ternesite hydration and comparing it with other methods in a suitable environment. Specifically, using the saccharate method, followed by the hydration of ternesite clinkers and the influence of calcium aluminate phases on the stability of thaumasite produced by the hydration of ternesite clinker. Subsequently, the phase composition was evaluated by X-ray diffraction analysis, in some cases by electron microscopy.