gemini surfactants are essentially two surfactants joined by a linking chain. We have extensively explored cationic geminis at the air/water interface and they exhibit a range of unusal behaviour and are still not well understood. We have found that the addition of electrolyte above the critical micelle concentration decreases the adsorption, although the surface tension also decreases (the two changes are generally considered to be incompatible). We attribute this unusual phenomenon to a structural change at the surface and we propose to use neutron reflectometry to explore the change.