A new representation combining network and stage-gate frameworks to study the impact of capital and research & development (R&D) decisions on the evolution of biomass to commodity chemicals system is presented. The network representation is used to universally express the interconnections between the processing technologies and to track the material flow among them. The stage-gate representation is used to express the discrete nature of technology maturity levels. The corresponding mixed-integer nonlinear program is developed and solved for a case study. In this case study, ethylene and propylene can be produced from naphtha and/or biomass. The results of the sensitivity analysis reveal that the raw material costs are the dominant factors that dictate the optimum investment decisions and production plan for this system. (C) 2013 Elsevier Ltd. All rights reserved.