Conditioning agents must adsorb to the surface of hair in order to perform effectively. The surface of the hair contains protein structures forming anionic centres. In instances of chemical damage, e.g. by bleaching, dying or perming, the number of anionic groups is even higher due to the generation of oxidised protein groups such as cysteic acid. Therefore cationic molecules are a preferred class of conditioning agents providing the required affinity towards hair. Cationic conditioners ensure a pronounced conditioning effect, especially on damaged areas. Conventionally available cationic modified polydimethylsiloxanes (Fig. 2) are composed either of unmodified linear siloxane backbones with quaternary groups at each end (?,?-modified siloxane) or comb-like modified siloxane chains with quaternary groups attached to the silicone chain. The undisturbed silicone backbone of the linear siloxanes provides a good conditioning effect, but each molecule possesses only two cationic groups at the sides which can cling to the hair’s surface. In the comb-like cationic siloxanes as well as in the frequently used amodimethicone derivatives, the silicone chains are disturbed by organic modifications and thus do not provide a conditioning effect that is as good as for the linear structures. On the other hand, more than two cationic anchor groups can be incorporated into the molecules leading to an improved substantivity. The technology of silicone quaternium- 22 represents a clear improvement over the traditional structures. The branched, T-shaped silicone backbone carries three quaternary groups, while at the same time the silicone domain is expanded in another dimension (Fig. 3). The length of the uninterrupted silicone chain is a decisive factor contributing to the exceptional properties of the product and guaranteeing good conditioning effects. Correspondingly, the T-shape further improves the already excellent characteristics of silicone conditioners while at the same time the increase in cationic centres enhances the adherence to hair and other protein surfaces. The composition of the silicone quaternium-22 is 65% active silicone quat and 35% PPG-3 myristyl ether. The substantivity of silicone quaternium- 22 on hair was confirmed by Confocal Laser Scanning Microscopy (CLSM).1 For this experiment a special derivative of silicone quaternium-22 was prepared and labelled with fluorescein, a fluorescent marker. This modified silicone quaternium- 22 was incorporated into a conventional conditioner rinse formulation. After application and rinsing of this test formulation, single hair fibres were examined with CLSM (Fig. 4). The reflection mode (a) shows the topography of the hair fibre. The image in fluorescence mode (b) shows the localisation of the labelled material on the same fibre area. This demonstrates that due to its unique triple cationic charge, silicone quaternium- 22 is highly substantive to hair out of a conditioner rinse application. Conversely, untreated hair, used as a control, did not display any fluorescence. The high substantivity of silicone quaternium-22 is the prerequisite for the extraordinary conditioning and protection effects which can be shown for the product.