Supercapacitors have long gained attention as disruptive devices that play in markets as varied as electronics and automotive. So far, their growth in mobile applications has been gradual, without the sudden explosion in market opportunity that many have touted in the past. Here we look at the current applications where supercapacitors have strong value, and the outlook for materials, cell, and system performance and cost improvements that may enable bigger and better opportunities down the road. We find that materials innovation and high-voltage operation will enable supercapacitor cell prices to fall by 15% or more over the next five years, but system costs will remain a significant obstacle. Transportation applications in passenger and bus hybrids will lead the way as the supercapacitor market grows to more than $0.8 billion in 2018.