Nowadays the requirements for knowledge of the composition, properties and behavior of existing and new material are demanded in materials production. Liveness and durability of plaster mixture is in the large part directly influenced by physico-chemical processes taking place in the initial stage of setting and hardening of mixture. Hydration process of lime mixture is an important milestone in plaster creating . At this stage there are formed crystalline hydrations products, which has significantly affect on the final properties of lime binders. Analysis of substances in any state shall be assured by infrared spectroscopy method. It is an analytical method designed especially for identification and structural characterization of organic compounds and for determination of inorganic substances, particularly in the branch of binders and materials used in their preparation.