Water in oil microemulsions have been formed for the first time with three anionic surfactants in alcohol/isooctane mixtures. The surfactants used were bis(2,4,4-trimethylpentyl) sodium phosphinate (NaPOO), bis (2,4,4-trimethylpentyl) sodium monothiophosphinate (NaPSO), and bis(2,4,4-trimethylpentyl) sodium dithiophosphinate (NaPSS). The effects on the formation of water in oil microemulsions of the concentration of NaCl in the aqueous phase and of the nature and concentration of surfactant and alcohol in the organic phase were comparatively studied. The three surfactants have two identical tails and differ in their polar heads; thus their comparative study gives some insight into the effect of the surfactant head group on the water uptake of water in oil microemulsions systems. The results show that, under well-defined conditions, these surfactants have the ability to solubilize a considerable amount of water in isooctane in the form of water in oil microemulsions.