Diffusion-ordered NMR measurements for aqueous solutions at 298 K containing oxyethylene spacer gemini surfactants (12-EOi-12), in the absence and presence of gamma-cyclodextrin (gamma-CD), were analyzed to determine the binding mode of the complex, and the effect of the complexation on the aggregation. The analysis of the self-diffusion coefficients reveals the formation of complexes of 1:1 stoichiometry (12-EOi-12:gamma-CD). This complexation is strong enough to destroy aggregates in an extension that confirms the 1:1 stoichiometry. The structure of surfactants and ROE enhancements point to a complex in which both hydrophobic chains thread one gamma-CD. (c) 2006 Elsevier B.V. All rights reserved.