This report analyzes developments in bio-based butanediol (BDO) technologies. BDO (both 1,4-BDO and 2,3-BDO) derived from bio-based materials or processes can be used as is or converted into a number of chemical products - potentially improving the GHG profile of the process. This study assesses the technical, commercial, and economic aspects of producing different isomers of BDO via bio-based sources or processes.