Blockchain is a hot topic. Until very recently, it was associated almost exclusively with cryptocurrency - bitcoin, ethereum etc. However, the power of blockchain to revolutionize the way we exchange goods and services, and transform how we govern - above and beyond the cryptocurrency hype - is increasingly being recognized. When it comes to cities, the transformative potential of this technology is enormous. From enabling P2P energy-sharing systems, as in New York’s ‘Transactive Grid’, which allows local residents to generate, buy and sell their own solar energy, to encouraging behavioral change - for instance through SocialCoin’s blockchain and AI-based ‘social good’ currency - and much more - blockchain is offering new opportunities to create more economically, environmentally and socially sustainable communities. As such, blockchain is likely to be an increasingly central enabler of smart city innovation worldwide. In this article, we will explore the potential benefits of blockchain in an urban context.