A surfactant composition including a C10 AOS and/or C12 AOS, and an effective amount of at least one solubilizing component so as to increase brine tolerance of the composition is disclosed. The solubilizing component comprises a mixture of






where X is H, an alkali metal, alkaline earth metal or ammonium, and R is a linear C6-C16 alkyl group. A method of recovering hydrocarbons from a reservoir during gas injection into said reservoir is also disclosed which involves at least periodically injecting the gas and a foam-forming surfactant composition into the reservoir so as to assist in the recovery of hydrocarbons from the reservoir.