It is possible to generate and screen new chemical reaction paths, on the basis of properties derived from the atom balance equation and algebraic-thermodynamic considerations in a standard Gibbs function of reaction-temperature space. When group contribution methods are used to provide standard Gibbs function of formation of the chemical species involved, the data back requirements decrease considerably. It is shown how DELTAG of species reaction can be systematically related to that of group reaction. In the particular case the group reaction has unique solution, whatever the degrees of freedom of the species reaction or the nature of the species, all DELTAG vs. T lines intersect in a (T(u)*,0) point. This point is calculated from group properties, resulting in significant computational economy in the search procedure.