Hydrodynamic and gas-liquid mass transfer parameters have been determined in common equipment, i.e. same column and liquid and gas distributors, for three cocurrent, upflow gas-liquid contactors : bubble column, fluidized bed and packed column. Two tracer analysis, one with an inert liquid tracer, the other one with a transferable gas tracer have been used in order to determine the parameters of the axial dispersion model : liquid holdup, gas and liquid axial dispersions, and gas-liquid mass transfer coefficient. The influence of gas and liquid velocities and particle diameters has been observed. The effects of additives as electrolytes or glycerol have been investigated.