Abstract Generalized geometric programming (GGP) problems occur frequently in engineering design, chemical process industry and management. Although some exponential-based decomposition methods have been developed for GGP problems, these methods can only handle problems with positive variables. Applying GGP in real applications, free variables are usually introduced to model the system behavior or the management problems. Therefore, this study proposes a technique for treating free variables in GGP problems. Numerical examples are also presented to demonstrate the usefulness of the proposed method.