Low-solubility-gas mass-transfer parameter determination has been achieved using conventional, and nonconventional, electrochemical, or predictive calculation methods. The methods have been compared for the oxygen diffusivity and solubility determination in alkaline media. Their validation has been fulfilled in the case of 1 M NaOH at 25 °C. Their use for membrane chlorine−soda process industrial electrolytes, 11.1 M (33 wt %) NaOH at 25 and 80 °C, has then been undertaken, leading to D_O2(80 °C) = 2.54 × 10^-9 m² s^-1 and He^-1(80 °C) = 1.17 × 10^-7 mol m^-3 Pa^-1, which is 72 times lower than that in 1 M NaOH at 25 °C.