The invention relates to a method for producing high-molecular weight, solid, meltable, thermoplastic, pre-ceramic polymers by converting liquid low-molecular weight polysilazanes in a solvent, in the presence of a catalyst, a stopping reagent stopping the reaction as soon as the desired degree of polymerization is achieved. The obtained polysilazanes can be processed by conventional industrial methods, such as, for example, extrusion, injection molding, melt spinning, calendering, film and hollow body blowing, rotational molding, fluidized bed sintering, flame spraying and transfer molding (RTM and DP_RTM).