The investigation of the effect of tempering on thermal analysis ofAl-Ti-Si alloy and its composites with MgO and SiC particles wasperformed. Thermal analysis was performed before and aftertempering by DSC scan. Optical microscopy was used to identify thephases and precipitations that may be formed in base alloy andcomposites. X-ray diffraction test indicated that the Al3Ti is the mainphase in Al-Ti-Si alloy in addition to form Al5Ti7Si12 phase. Somechemical reactions can be occurred between reinforcements andmatrix such as MgO.Al2O3 in Al-Ti/MgO, and Al4C3 and Al(OH)3 inAl-Ti/SiC composite. X-ray florescence technique is used toinvestigate the chemical composition of the fabricated specimens.Heat treatment (Tempering) changes the microstructure of base alloyand its composites which was assessed by DSC scan. Generally,three main peaks appeared in DSC represented by GP zone, S phase(precipitations) and dissolution of phases or precipitations. Aftertempering, composite with SiC particles showed better results thanbase alloy and composite with MgO. Since the optical microscopyrevealed reforming the stable phase Al3Ti with evaporation somegases from composite. DSC analysis showed the stability ofcomposite with SiC was up to 270oC.