The modified blade turbines as attractive alternatives to the standard Rushton turbine do not require any modification in the electrical engine motor and drive assemblies, are simple to manufacture and have a reduced power consumption. The modified blades were obtained through increase of the blade height of the Rushton turbine simultaneously with perforation of the blade surface. The field surface of the modified blade is equal to the blade surface of the standard Rushton turbine. Gas-liquid mass transfer in a mixing vessel using standard and modified Rushton turbine agitators, positioned singly or doubly on the same shaft, were investigated. The empirical equations for the volumetric mass transfer coefficient were expressed depending on the power input per unit volume, the gas superficial velocity, the number of turbines and their type indicated by the surface fraction of the perforations S-G/S-C having values between 0-0.588. The TP3 modified turbine with the surface fraction of the perforations S-G/S-C = 0.353 is optimum on the basis of the mass transfer efficiency.