The gas behavior in gas-liquid reactors stirred with multiple Rushton turbines was studied. Equipment of two scales and several aspect ratios as well as liquids of different characteristics were used. The gas behavior is modeled with the simple axial dispersion model. Its suitability for these systems is evaluated by means of two different experimental techniques-a dynamic one and steady-state one. The model proves good for water, acceptable with coalescence-inhibiting electrolyte solutions, and rather questionable with viscous liquids. Constant tip speed is an appropriate scale-up criterion for the model parameter-at least for coalescent systems. A tentative correlation is also proposed to account for the number of turbines. Scrutinity of the experimental results reveals the model drawbacks.