The invention concerns the gelatinization of viscous aqueous or hydroalcoholic liquid components, buffered or not, intended for the production of films for the manufacture of soft capsules. These compositions are notable in particular in that gelatinization thereof is obtained extemporaneously starting with thickening agents that exhibit the unique property of gelatinizing instantly upon contact with complexing solutions, the elasticity of the films being obtained by introducing or not introducing a plasticizing agent, decomposition thereof being controlled by incorporating or not incorporating a surfactant or a polysaccharide, and preservation thereof being ensured or not ensured by the addition of preservatives, thus allowing it to contain oily and/or aqueous solutions. The invention also concerns a method for manufacturing films for such capsules, which comprises gelatinization of said films by applying a complexing agent to the mass by spraying and/or by immersion. Applications: pharmaceuticals, cosmetics, and foods.