Basalt represents one of the most common stones used in the construction of our archaeological structures. However, basalt is a very dense, compact and hard igneous stone; it is highly deterior-ated by physicochemical deterioration factors especially in the open air environments. Cracks are among the dangerous deterioration aspects in basaltic stones. They significantly contribute to accelerate their deterioration rates. Consequently, the cracks in basaltic stones have to be filled with a suitable mortar to stop their harmful impacts. In the present work, four types of organic binder based mortars were prepared and comparatively evaluated to select the best one for filling the cracks occurring in the studied archaeological basaltic stones at Abu Sir area. Examinations and analytical study were performed using transmission electron microscope, polarizing microscope, x-ray diffraction, colourimetric measurement, static water contact angle, compressive strength and scanning electron microscope attached with EDS. The results declared that the mortar named M4 (Acryclirsil + basaltic powder) is the most suitable composite for filling the cracks in the studied basalt.