A thickener and surfactant for a driving fluid used in enhanced oil recovery comprises a salt of a sulphated polyoxyethylene alcohol in which at least 40 wt % of the alcohol portion of the sulphated polyoxyethylene alcohol is a C.sub.8 to C.sub.20 primary alcohol having a C.sub.1 to C.sub.3 alkyl substituent in the 2-position of an otherwise linear chain. The balance of the alcohol portion may be made up of a linear primary alcohol of same carbon number as the 2-alkyl branched alcohol.