Method for preparing soluble molecular complexes (A) that consist of at least one active substance (I), poorly soluble in aqueous medium, incorporated into one or more host molecules (II). (I) and (II) are mixed then subjected to a molecular diffusion step in which the mixture is contacted, in static mode, with a dense fluid (III) under pressure, in presence of at least one diffusion agent (IV), then (A) recovered. An independent claim is also included for (A) prepared by the new method.
