Among various renewable and sustainable energy sources being explored, biobutanol has been recognized as one of the promising alternatives for biofuels due to its attractive physical and chemical properties. Various inventions have been reported for the biological production of butanol, maintaining its competitiveness in efficiency, economy, and production scale. This article reviews such patented inventions and relevant research achievements to the microbial strains and fermentation processes for the enhanced production of biobutanol. We also discuss current challenges for strain improvement based on recent developments.