"Financial Cryptography and Data Security" is a comprehensive collection of research papers that emerged from the 19th International Conference on this topic. The conference took place in January 2015 in San Juan, Puerto Rico, and brought together experts from around the world to discuss current developments and challenges in the field of financial cryptography and data security. This publication includes 23 revised full texts and 10 short contributions selected from a total of 102 submitted papers. The contributions are organized into various thematic sections addressing important aspects such as side channels, cloud cryptography, payment and fraud detection, authentication and access control, as well as mobile security solutions. This collection offers valuable insights into the latest trends and technologies that contribute to securing financial transactions and protecting sensitive data.