A study has been carried out on the modification of surface tension in aqueous solutions of the collector sodium oleate, with temperatures in the bath ranging between 293 and 323 K, and pH between 4 and 12. The results obtained indicate that surface tension is greatly affected by these two parameters. As temperature is increased in the bath, the surface tension of the solution decreases in all cases for the range of sodium oleate concentrations between 7.3 x 10(-6) and 6.2 x 10(-4) M. Minimum values for surface tension were also found to shift toward the pH 10 value as the agent concentration is increased, regardless of the temperature of the solution. Certain thermodynamic magnitudes associated with the adsorption of sodium oleate at the solution-air interface were also obtained. A decrease in free standard energy was also noted on adsorption of the surfactant at this interface.