Precise measurements on the density of sodium lauryl sulfate in pure water and in methanol (1) + water (2) mixed solvent media containing (0.10, 0.20, 0.30, and 0.40) volume fractions of methanol at (298.15, 308.15, 318.15, and 323.15) K are reported. The concentrations are varied from (0.3 3 10 À1 to 1.3 3 10 À1 ) mol 3 kg À1 . The results were almost constant on the partial molar volumes with increasing surfactant concentration. Also, the partial molar volumes are found to increase with increasing temperature over the entire concentration range investigated in a given mixed solvent medium and are found to decrease with increasing methanol content in the solvent composition.