This article presents an experimental study on the influence of the surfactant Sodium Laureth Sulfate (SLES) on the kinetics of oxygen mass transfer into water during bubble aeration. Experiments were performed in a 40 L cylindrical column equipped with a fine-bubble disc diffuser at an air flow rate of 4 L/min and a temperature range of 12–18 °C. Test series were conducted with an SLES concentration of 60 mg/L. The time-dependent dissolved-oxygen concentration was recorded with dedicated probes, allowing characteristic aeration curves to be obtained and the overall volumetric mass-transfer coefficient KLα to be determined via the linearised relationship log(Cs − Ct). A temperature correction factor θ = 1.024 was applied to normalise the values to 20 °C. On the basis of KLα, the standard oxygen transfer rate (SOTR) and standard oxygen transfer efficiency (SOTE) were calculated. The results show that adding SLES to water decreases the saturation concentration Ct from 4.88 to 4.45 mg/L (−8.8%), reduces KLα from 0.01209 to 0.01161 s−1 (−3.96%), and lowers the SOTR from 0.02066 to 0.01984 kg O2/h (− 4%). The time required to reach 70% of total saturation was up to 20% longer compared with clean water. The findings indicate that even low SLES concentrations can raise the energy demand of aeration systems. Practical recommendations include applying preliminary degassing or physical filtration of organic matter to restore oxygen-transfer characteristics close to those observed in clean water. Future research should elucidate the mechanisms by which surfactants affect gas–liquid dynamics and develop methods to compensate for their negative impact.