NdFe10.75Mo1.25 and NdFe11Ti alloys have been successfully nitrogenated by heating a mixture of powdered alloys with sodium azide (NaN3) at temperatures between 330 and 450°C. Among the characterization techniques used to evaluate the final product, Mössbauer spectroscopy was invaluable for quantitative determination of 1-12 and α-Fe phases, after and before nitrogenation. The α-Fe phase increased indicated that a competition between the interstitially modified compound formation (alloy + N) and alloy dissociation occurred. This effect was more pronounced in Ti alloys nitrogenated at 450°C.