An experimental program has been initiated to evaluate the performance of a reciprocating plate bioreactor for its use in viscous fermentations. The investigation is divided into three parts : (1) to study the hydrodynamics within the bioreactor, (2) to determine the axial dispersion coefficient and the overall oxygen mass transfer coefficient as a function of the operating conditions, and (3) the evaluation of a reciprocating plate column as a bioreactor for viscous fermentations. This paper reports on the determination of the axial dispersion coefficient and on the measurement of the overall oxygen transfer coefficient. Experiments were done in water on a semi batch scheme (no water flow) in a 1.26 m high and 101.6 mm internal diameter column. It was found that the axial dispersion coefficient is a strong function of the reciprocation speed whereas it is relatively unaffected by the aeration flow rate. The overall oxygen transfer coefficient was determined with two separate methods : (1) the sulfite oxidation method which is based on the conversion of sulfite into sulfate to calculate the overall oxygen transfer coefficient, and (2) the gassing-out method which uses dissolved oxygen responses at various locations inside the column to determine the local mass transfer coefficient. It was found that higher values of the oxygen transfer coefficient prevail within the reciprocating plate bioreactor than in other types of mixing devices, for an identical volumetric power input.