Alkaline flooding is a method of enhanced oil recovery, in which alkali reacts with acidic components in the crude oil to form surface-active substances. In the present study, the interaction between alkali and crude oil was studied by measuring their physicochemical properties. A Fourier transform infrared (FTIR) spectrum of the crude oil reveals the presence of carboxylic acid groups leading to in situ formation of surfactants, which in turn decreases the interfacial tension between oil and water and other petrophysical properties responsible for better oil recovery. The effectiveness Of alkali on enhanced oil recovery was tested with three sets of flooding experiments performed in the sand-pack systems. Substantial additional recoveries (more than 15% of original oil in place) over conventional water flooding were obtained in the present investigation.