Mondex is a smart cardelectronic cash system, implemented as a Stored-value card. Conceived by Tim Jones and Graham Higgins of the National Westminster Bank (now part of the RBS Group) in the United Kingdom. The system was initially developed between 1990 and 1993, with internal trials being carried out by approximately 6,000 London-based National Westminster staff from 1992. The system was publicly unveiled in the December of 1993. Initial public trials of the payment system were carried out from July 1995, by the newly incorporated Mondex International, in Swindon, UK. The public phase had required the development and manufacture of numerous merchant devices and smart cards, with BT, the National Westminster and Midland (HSBC) Banks sponsoring and installing retail terminals at the car parks, payphones, buses and 700 of the merchants in the town, and mondex cards to the residents. The system was subsequently sold to MasterCard International in 1996 (completed February 1997). Mondex launched in a number of markets during the 1990s, expanding from an original trial in Swindon, UK to Hong Kong, Guelph, and New York. It was also trialled on several British university campuses from the late 1990s, including the University of Edinburgh, University of Exeter (between 1997 and 2001), University of York, University of Nottingham, Aston University and Sheffield Hallam University.
The Z notation was used to prove security properties about Mondex, allowing it to achieve ITSEC level E6, ITSEC's highest granted security-level classification.