Understanding micellization processes at the molecular level has direct relevance for biological self-assembly, folding, and association processes. As such, it requires complete characterization of the micellization thermodynamics, including its correlation with the corresponding structural features. In this context, micellization of a series of model non-ionic surfactants (poly(ethylene glycol) monooctyl ethers, C8EY) was studied by isothermal titration calorimetry (ITC) and differential scanning calorimetry (DSC). The corresponding structural properties of C8EY micelles were investigated by small-angle X-ray scattering (SAXS). The C8EY micellization, characterized independently from ITC, DSC, and structural data, reveals that Delta H-M degrees > 0, Delta S-M degrees > 0, and Delta C-P,C-M degrees < 0, while the dissection of its energetics shows that it is primarily governed by the transfer of 20-30 C-8 alkyl chains from aqueous solution into the nonpolar core (r approximate to 1.3 nm) of the spherical micelle. Moreover, thermodynamic parameters of micellization, estimated from the structural features related to the changes in solvent-accessible surface areas upon micellization, are in a good agreement with the corresponding parameters obtained from the analysis of ITC and DSC data. We have shown that the contributions to Delta S-M degrees other than from hydration (Delta S-M,S-other), estimated from experimental data, appear to be small (Delta S-M,S-other degrees < 0.1 Delta S-M degrees) and agree well with the theoretical estimates expressed as a sum of the corresponding translational, conformational, and size contributions. These S Delta(M,other)degrees contributions are much less unfavorable than those estimated for a rigid-body association, which indicates the dynamic nature of the C8EY micellar aggregates.