Abstract This paper describes the effect of high temperature on the hydration characteristics of artificial pozzolanic cement pastes containing metakaolin with or without silica fume for different hydrothermal ages in well closed stainless steel capsule. Pastes were hydrothermally treated in well closed stainless steel capsule at 180 °C for different hydrothermal ages (2, 4, 6, 12 and 24 h). Hydration characteristics of the hydrothermal OPC–MK–SF pastes were studied by the determination of compressive strength, bulk density, porosity and chemically combined water contents at different hydrothermal ages. The phase composition and morphology of the formed hydrates were studied using X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). Results indicated that the compressive strength of multi-blended mixes containing silica fume 5% is by mass higher than the corresponding Portland cement control at later age up to 6 h of hydrothermal curing age.