A rapid and internally consistent technique has been developed to measure the volumetric oxygen transfer coefficient, k(L)alpha, in fermentation systems. The method consists of tracing the dissolved O-2 concentration of the fermentation broth during a short interruption of the aeration. The O-2 concentration trace thus obtained can be analyzed to determine the values of k(L)alpha. Additional experiments on prolonged O-2 starvation, carried out to find the limitation of the technique, suggest that O-2 uptake rate will vary if a prolonged (2-10 min.) O-2 starvation occurs.