In this paper, a study on the global gas holdup and hydrodynamic flow regimes developed in a partially aerated bubble column at variable air superficial velocities (U-G) in the presence of positive and negative surfactants is presented. According to the results obtained, despite the different liquid phase properties variation caused by the presence of positive (alcohols) and negative (electrolytes) surfactants, both reduce coalescence and the effect in the gas holdup (epsilon(G)) is equivalent: it increases with the surfactant concentration (C) but only when the (C/C-t) ratio is clearly above 1, being C-t the transition concentration. Contrary to the results obtained for totally aerated bubble columns, for lower values of the (C/C-t) ratio, the holdup remains practically invariable. Considering the crucial role that C and C-t play in the resulting epsilon(G), a new prediction equation for epsilon(G) accounting for the ratio (C/C-t) and U-G is presented and its performance for both types of surfactants validated. Additionally, visual and wall pressure fluctuations studies reveal that the vortical flow (VF), characterized by an oscillating bubble plume, prevails in ultrapure water (UPW) but results destabilized in the presence of surfactants. This destabilization results in an evolution to a pseudo-steady flow regime, the double cell turbulent flow regime (DCTF), characterized by a quasi-static bubble jet, located at the column centerline that determines the appearance of two static symmetrical vortices (C) 2011 Elsevier Ltd. All rights reserved.