The impact of high temperatures on calcined clay-limestone cement concrete (LC3) and calcined clay-marble stone cement concrete (MC3) is studied in this paper. In the present study, M25 and M35 grades of concrete was prepared using LC3 and MC cement and ordinary Portland cement (OPC). After 28 days of moist curing, prepared cubes of size 100 x 100 x 100 mm(3), which were subjected to 100 degrees C, 200 degrees C, 400 degrees C, 600 degrees C and 800 degrees C temperatures. Scanning electron microscopy (SEM), mass loss, surface texture and compressive strength (CS) were studied before and after specified temperatures. The X-ray diffraction (XRD) patterns, thermogravimetric analysis (TGA) and Fourier transformed infrared (FTIR) spectroscopy have been studied over M25-OPC, M25-LC3 and M25-MC3 concrete. The result shows that when the temperature exceeds 400 degrees C, the mass loss in OPC was more than LC3 and MC3 concrete. CS was more in LC3 and MC3 concrete than OPC concrete at all high temperatures. The SEM results reveal that M25-LC3 and M25-MC3 concrete specimens have a sound structured C-S-H gel at high temperatures as compared to M25-OPC concrete specimens.