The use of adjusted/optimized saline water categorized into two different classes namely smart water (SW) and low salinity (LoSal) water injection has been proposed for more oil recovery from specific types of oil reservoirs. There are possible mechanisms concerning SW flooding that have been proposed in the literature, some of them are still subject to more examination. In this study, an experimental investigation is performed to determine the influence of type and amount of salt to the surface properties including interfacial tension (IFT) and contact angle (CA) of aqueous solution + acidic and asphaltenic crude oil + carbonate rock systems. For this purpose, the concentration of different salts including NaCl, KCl, Na2SO4, MgSO4, CaSO4, CaCl2, and MgCl2 are examined in a wide range of concentrations. The measurements revealed that salinity has dual impacts on the CA of water wet surfaces of carbonate rock. That is, CA could remain unchanged or increase as a function of brine salinity, though the increase was still within the strongly water-wet region of wettability with high film stability. The results of IFT measurements show that using ions especially divalent cations in the presence of chloride anion could substantially decrease the IFT values. The results show that the lowest IFT values are obtained at high salinity conditions (above 0.053 mol.kg(1)) especially if divalent ions of MgCl2 are utilized. High values of IFT are obtained if monovalent salts such as NaCl and KCl are used.