Steady-state dynamic aqueous foams were generated from surfactant free dispersion of aggregated anatase nanoparticles (in the micron size range). In order to tune the particle surfaces, to ensure a critical degree of hydrophobicity (so that they disperse in water and generate foam), the particles were subjected to low temperature plasma treatment in the presence of a vapour phase silane coupling agents. From ESCA it was shown that hydrophobization of the surface only occured at a small number of sites. Foamability (foam generation) experiments were carried out under well defined conditions, at a range of gas flow rates using the Bikermann Foaming Column (1). The volume of the steadystate foams were determined under constant gas flow conditions but on removing the gas flow, transient foams with short decay times (< 5 s) were observed. The foamability of the steady state foams was found to be dependent on (a) the time of plasma treatment of the particles (surface hydrophobicity), (b) the particle concentration in the suspension and (c) the state of dispersion of the particles. High foamability was promoted in the pH regions where the charged particles were less hydrophobic and more highly dispersed. In the pH regions where the particles were more hydrophobic and colloidally unstable, the foamability was considerably reduced.