Ultracapacitors have been under development for over two decades and recently have received attention for their commercial applications in products such as hybrid electric vehicles, medical devices, grid energy storage, and personal electronics. Ultracapacitors are attractive for their ability to quickly deliver large quantities of power, making them an ideal complement to battery technology in comprehensive power systems. Recent technical advancements have developed ultracapacitors with performance that is now viable in a variety of commercial applications. This research uses publication, patent and investment data to identify and trace the commercial pathway for this emerging technology. The firms and industries currently developing and commercializing ultracapacitors are identified using affiliation data. To date, ultracapacitor R&D has been primarily performed by large multinational companies with broad energy-based product portfolios and emerging venture-backed capacitor companies. Firms in industries including transportation, consumer electronics, and medical equipment have researched how ultracapacitors can be integrated into power systems. The early stages of ultracapacitor development are compared with Li-ion and NiMH batteries and evidence shows similarities between the early stages of the commercially successful Li-ion battery.