This thesis explores the new context of digital payments related to the innovative invention of Bitcoin. In a financial and economical context, which is trying to get out of crysis, new tools and new way of payments are emerging. The result of this analysis is a service design that tries to mediate between the new innovations and old systems, in order to generate new behaviours in the context of mobile and digital transactions. The research part provides an overview of the traditional financial system situation (banks), and the new emerging technologies, starting from mobile payment systems arriving to the creation of new, digital and international currency as Bitcoin’s protocol. It is important to understand that a revolution is happening in the world of economics and finance, and young startups are trying to steal part of the market from old and no-up-for-innovation companies like banks and exchange systems. The phenomenon started with well-known names, like PayPal. And now it is evolving and growing due to the birth of new technology such as NFC, infrared or Touch ID. Companies like Simple, ApplePay, Dwolla etc. are forcing their way into the market with branded new services, close to a more user-centred design perspective. And if this doesn’t seem enough, the great invention of mathematical currencies is getting more and more concrete and known. Commissions on transaction and exchange of currency are a big problem for small and medium businesses, since their client mostly pay by credit cards. Bitcoin’s protocol was born in order to change completely the existing system, and put money in people’s hands; this thanks to a new kind of currency, which is completely digital, not dependent from any central control (and free from commissions on transactions), more efficient and international. Thanks to the prototype phase, the efficiency and the potential of cryptocurrencies was proven. The collaboration with Robocoin, a sturtup which sells bitcoins ATM machines, demonstrated that in order to make a revolution happen is necessary to start from a traditional behaviour. Complex inventions need to be introduced into society with a medium that reminds of a daily routine. The bitcoins ATM machine had a great success since it brought to people a new idea of transacting with different currency by using an already existing and easy to use tool. Another thing that the prototype phase has shown was that if the usability of Bitcoin is quite feasible, volatility is still a problem that needs to be solved. The solution phase is the core of this thesis research. It is possible to avoid Bitcoin’s volatility using a human centred service design approach. Bitlocker has been designed in order for people to save money, transact in a better, faster and more efficient way. Thanks to an appealing application (with a related platform), which transforms traditional currency into bitcoins at the moment of the transaction, users will enjoy the benefits of bitcoin with the familiarity and stability of the money they use every day.