E-transactions systems involve three or more partners in the exchange and sharing of information concerning trades, payments, services and other activities. These include customers communicate through architectures to service providers. We can consider that e-transactions evolve in an area where all these partners collaborate toward achieving similar objectives. As a consequence, this collaboration leads to the creation and modification of messages by each middle agent (as in, for example, transaction amount, consumer name, some public certificates, and so on). The e-transaction process is a complex one because it has, for instance, numerous exchanges between the different partners. There are many applications of e-transactions systems such as e-commerce, e-administration, e-medical, e-science, e-government … Many aspects contribute to the functioning of e-transactions systems such as security aspects (authentication, confidentiality, ...), architecture (such as Cap, 3D secure, ...), privacy of the cyber-consumer, responsibility level of the different partners, benefits of new technologies (mobile, contact-less, biometrics), and many possible application domains. We invite original contributions from researchers in academia, research institutions and industry on these emerging and important areas of information technology. This Workshop on E-Transactions Systems - to be held as part of the 2015 International Conference on Collaboration Technologies and Systems (CTS 2015) - will focus on many topics, some of which are listed below.