In mineral flotation and de-inking flotation, the surface tension of the process water is an important parameter to study, since it is influenced by the concentration of frothers, collectors and other surfactant species. This influences the bubble size, froth stability, and the bubble/particle attachment, which have a direct influence on the overall plant performance. Also, since flotation processes operate under dynamic conditions then surface tension measurements, determined within short time spans (milliseconds to seconds) are often more informative than equilibrium values. In this paper, we review our recent dynamic surface tension studies with aqueous solutions of (a) fatty acid; representing a model collectors/frothers (b) polyethylene oxide; representing a model frothers/dispersants and (c) ethyl carboxyl ethyl cellulose (EHEC); representing a model polymeric organic modifying agent (dispersants/flocculant) were studied using the "maximum bubble pressure technique". Finally, we discuss the development of a new dynamic on-line surface tension monitoring system, at the Institute for Surface Chemistry.