A new nonlinear inversion procedure, applied to recover the spherical potential energy function from second virial coefficient experimental data, is presented in this work. For a Lennard-Jones potential as an initial guess, it was possible to produce another potential with an error for the second virial coefficient comparable with the experimental data. The algorithm is stable, simple, can be adapted to improve existing potential energy functions or to invert other properties in a nonlinear representation. (C) 2003 Elsevier B.V. All rights reserved.