In this work, the gas-liquid mass transfer in a lab-scale fibrous bed reactor with liquid recycle was studied. The volumetric gas-liquid mass transfer coefficient, k(L)a, is determined over a range of the superficial liquid velocity (0.0042-0.0126 m.s(-1)), gas velocity (0.006-0.021. m.s(-1)), surface tension (35-72 mN/m), and viscosity (1-6 mPa.s). Increasing fluid velocities and viscosity, and decreasing interfacial tension, the volumetric oxygen transfer coefficient increased. In contrast to the case of co-current flow, the effect of gas superficial velocity was found to be more significant than the liquid superficial velocity. This behavior is explained by variation of the coalescing gas fraction and the reduction in bubble size. A correlation for k(L)a is proposed. The predicted values deviate within +/- 15 % from the experimental values, thus, implying that the equation can be used to predict gas-liquid mass transfer rates in fibrous bed recycle bioreactors.