Consumption of water during hydration reactions, or water evaporation through the surface results in the development of negative pressure in capillary pores of concrete at early ages. This pore water potential (PWP) creates early-age shrinkage strain and increases the chance of early-age cracking. The aim of this study is the investigation of the effects of internal curing (IC), water-to-cementitious materials ratio (W/CMs) and incorporation of supplementary cementitious materials (SCMs) on the hydration reactions and PWP development in cement-based materials. For this purpose, 15 mortar mixtures with different W/CMs (0.3, 0.375, 0.45 and 0.525), lightweight fine aggregate (LWFA) substitutions (10, 20, 30 and 50%) and SCMs incorporation (7.5% silica fume and 20% fly ash), as well as, 14 concrete mixtures with different W/CMs (0.35, 0.42 and 0.5), LWFA substitutions (10, 20, 30 and 40%) and SCMs incorporation (7.5% silica fume and 20% fly ash) were made and evaluated through isothermal calorimetry and pore water potential tests. The results demonstrate that IC is efficient in both promoting hydration kinetics and suppressing PWP development, especially for the mixtures with low W/C or incorporating silica fume.