Synthesis of (NH4)(4)ThF8 by a solid state reaction of ThO2 and NH4HF2 and the formation of ThNF by ammonolysis of (NH4)(4)ThF8 and ThF4 under different experimental conditions were investigated. The solid state reaction of ThO2 with NH4HF2 led to the terminal product (NH4)(4)ThF8 through a known intermediate (NH4)(3)ThF7 and most likely two other unknown chemical phases as determined by X-ray powder diffraction. Conversion of (NH4)(4)ThF8 into ThNF occurs through a ThF4 intermediate phase. Studies on the ammonolysis of ThF4 revealed it converted into ThNF through a continuous formation of low-stoichiometric thorium-nitride-fluorides such as ThN0.79F1.63 and ThN0.9F1.3. Thermal behavior of ThNF was also examined under different atmospheres and temperatures, with evaluation of formation kinetics. The ThNF decomposed to low-stoichiometric thorium nitride fluorides (ThNx/3F4-x) under different environments up to 1100 degrees C. Significant morphological changes in the products compared to that of the precursors confirmed the reaction steps involved. Microstructural characterization of (NH4)(4)ThF8 and ThNF were performed by HRTEM and are presented in this work for the first time. The (NH4)(4)ThF8 product was shown to contain polycrystalline characteristics in the majority of its nanostructure. On the other hand, ThNF has a high order of nanostructure, which explains the high thermal stability of the compound up to 1100 degrees C and the difficulty of making ThNx, in initial target product, from the described experimental conditions.