Molecular integral equation theory is inverted with respect to the calculation of effective potentials for a coarse-grained, reduced molecular model composed of fewer sites than the reference. The methodology is applied to an aqueous solution of cyclohexanol as a model case, the quality of the effective potentials is studied by extensive molecular dynamics simulations. Practical guidelines for the choice of reduced model sites are worked out and perspectives for mesoscale modelling are discussed. (c) 2005 Elsevier B.V. All rights reserved.