We have investigated the structural modifications of aqueous gelatin solutions for various thermal treatments and different concentrations. The structure is explored at different microscopic levels, putting into evidence the conformational coil ⇄ helix transition of the proteic chains (by optical rotation), the supramolecular structure of the network (by electron microscopy) and the role of solvent (by proton nuclear magnetic resonance). The non-equilibrium nature of the gel phase is demonstrated as well as its disordered character. A phenomenological analysis of the kinetics of helix formation is proposed, followed by an attempt for a microscopic modelling of the mechanisms, based on the data presently known.