Oxygen phase transfer plays an essential role for successful application of enhanced aerobic biodegradation (e.g. biosparging, oxygen bubble walls) for dissolved organic contaminants in groundwater. The key parameter for the efficiency of these in situ technologies is the microscopic transfer coefficient a.. For air injection in stagnant water Rutherford & Johnson (1995) observed experimental values between 3 and 7∙10^-8 m/s. Recent experimental and theoretical investigations (Donaldson et al., 1997) indicate that for column experiments with a water velocity u ~ 4m/day the transfer coefficient is by 2 orders of magnitude larger (α. = 2·10^-6 m/s ). In order to prove this important conclusion, we have calculated the breakthrough curve once again both in constant volume- and in constant pressure approach. Based on our calculations we reinterpret the experimental results of Donaldson et al. and obtain α = 6·10^-8 m/s. The reason for this discrepancy is that Donaldson et al. used the wrong differential equation for the residual gas phase. First results of a kinetic model of a recative oxygen wall for oxygen transfer and oxygen consuming reactions are discussed.