the viscosity peak shifts to lower hydrophobic surfactant composition and the degree of the viscosity peak shift is the largest for the linear-chain molecules and smaller for the branched or cyclic molecules. Dynamic frequency tests show that the zero-shear viscosity behavior for different high-polarity perfume and oil systems varies due to the change in the relaxation time behavior. The linear-chain molecules can penetrate well in the palisade layer of micelles and the penetration could be interrupted by branched or cyclic molecular architecture. On the other hand, by adding low-polarity perfumes and oils (p-cymene, hexahydrocumene, butylbenzene, d-limonene and decane), the behavior of the viscosity curve is quite different for decane and for other molecules, i.e. decane decreases the viscosity peak without shift of surfactant mixing fraction whereas other molecules behave as high-polarity molecu