Serapis Temple, which was constructed in the Roman Period and reached our present time, is one of the most important monuments of the world heritage. We must hand over this monument to next generations. This requires the identification of the characteristics of original construction materials and their deterioration problems for preventive measures.In this study, characteristics of bricks, mortars and plasters used in the Serapis Temple have been determined in order to have the necessary information of the characteristics of the intervention materials, which will be used in the conservation works of the temple. For this purpose, Roman, Byzantine and intervention bricks, mortars and plasters were collected for the laboratory analysis.Several analyses were carried out to understand their basic physical properties, microstructural features, and mineralogical and chemical compositions.Experimental results of the study indicated that Roman and intervention bricks are low dense and high porous. Raw materials used in their manufacturing were calcium poor clays and their firing temperatures did not exceed 900 C.Roman and Byzantine mortars and plasters are stiff, compact, low dense and high porous materials. They have high compressive strength values. But, intervention mortars are not stiff and compact and they have very low compressive strength.The mortars used during the late restoration works (1940) were manufactured by using lime and cement. Due to the use of cement, they contain a high amount of soluble salts compared to the Roman and Byzantine ones.The results of this study indicated that intervention materials should be compatible with the original materials and they will not give any damage to the original ones. This requires knowing about both the composition and physical properties of original materials as well as the problems of deterioration.