The formation of self-assembled structures triggered by pyridinium-based gemini guests in the presence of a sulfonato-calix[4]arene receptor has been thoroughly examined via isothermal titration calorimetry (ITC) in neutral aqueous solution. Data confirm the existence of a 1:1 host guest complex, in which the guest is strongly bound to the host cavity, and the formation of a 2:1 capsular-like adduct. The splitting of the Delta G degrees term into the enthalpic and entropic contributions allowed to highlight the often opposing forces driving the encapsulation process which strongly depend on the size and shape of the gemini guest.