The measurement of oxygen transit time from the disk to the ring of a rotating ring-disk electrode has been used for the oxygen diffusivity determination. The oxygen solubility has then been deduced from the limiting current measure in quasi-steady state oxygen reduction voltammetry. The method validation has been done for a 1 M NaOH solution at 25 degrees C. Its use in the case of industrial electrolytes, 11.1 M (33 wt.%) NaOH at 25 and 80 degrees C for which no literature data are available, has then been undertaken; the oxygen solubility is 72 times smaller than in 1 hi soda at 25 degrees C.