Attempts to increase the stability of photocatalytically active nanodispersions of titanium dioxide over a wide range of pH (3 – 10) were undertaken. Polyethylene glycols (PEGs) with di ff erent molecular weights and polyoxyethylenesorbitan monooleate (Tween® 80) were tested as stabilizing agents of TiO 2 nano- particles. The results of DLS measurements proved the stabilizing e ff ect of Tween® 80 while the systems involving PEGs, independently of the polymer concentration, showed a tendency to form aggregates in neutral solutions. The colloids stabilized with Tween® 80 were photosensitized with 2,3-naphthalenediol (nd) or 2-hydroxy-3-naphthoic acid (hn) or catechol (cat). The photocatalytic activity of such colloids has been assessed in an azure B degradation reaction using both UV and visible light. The nd@TiO 2

• Tween colloid appeared particularly photoactive upon visible light irradiation. Moreover, the comparison of activi- ties of nd@TiO 2
• Tween and TiO 2
• Tween revealed a signi fi cantly better performance of the former nanodispersion, independently of the irradiation conditions (UV or visible light). This e ff ect has been explained by di ff erent structures of micelles formed in the case of TiO 2 and nd@TiO 2 stabilized with Tween® 80.