A method for determination of quantitative distribution of promoters in various crystallographic phases of the catalyst precursor for ammonia synthesis was elaborated. XRD, AES-ICP and manganometry were used in the studies. Based on this method, it was established that calcium contained in the iron catalyst precursor for ammonia synthesis is in 64% located in the intergranular spaces. The content of calcium in Fe3O4 amounts 0.63 wt.%, which constitutes 21% of the total calcium. However, 15% of calcium is dispersed in the Fe1-xO phase, the concentration of which in this phase amounts 4.9 wt.%. Aluminium is located in the intergranular spaces in 9 wt.%, the remaining aluminium forms a solid solutions with magnetite. Potassium is completely located in the intergranular spaces. However, 91 wt.% of potassium is not bound with iron compounds, and is readily soluble in water.