A newly developed gas-induced reactor, characteristics of having a draft tube and dual turbines was studied. This paper presents the effects of operational variables on the onset of gas induction and power consumption post gas induction. Moreover, gas holdup and mass transfer were also investigated. It was found that all the impeller speed, the liquid level and the impeller diameter had significant effects on the onset of gas induction and the power consumption post gas induction. Two empirical equations which correlate the onset of gas induction and power consumption post gas induction with the operational variables were obtained, being successfully capable of predicting the data. The volumetric mass transfer coefficients (k(L)a) of 0.8-1.2/min and liquid-film mass transfer coefficients (k(L)) of 2.5 x 10(-4)-7.5 x 10(-4) m/s were also obtained, being comparable to the cited values. Furthermore, regional bubble number and size distributions as well as an unique method for determining the gas holdup were also presented.