The results of chemical analysis and investigation of mineralogy, as well as technological, electron-microscopic and fluoroscopy studies are presented in this article in order to identify the material and quantitative compositions of ancient mortars applied in the early medieval monasteries of Armenia. The specimens of binders selected from the walls, foundations and other locations of various buildings belonging to Dadivank and Tatev monastic complexes are investigated. The quantitative ratio of binders and sand, the chemical and mineralogical compositions of ancient mortars are identified, as well as their density, strength and water resistance.