Mondex是一款使用智能卡的电子收费系统，最初于1990年由英国国民西敏银行开发，经过5年的试验，于1995年开始于Swindon作测试，及后多个国家及地区均引进这套系统。1996年万事达国际组织买下了Mondex 51%的股份。1997年，英国的De La Rue公司成为了Mondex的合作伙伴。

但Mondex在香港则不太流行，在付款的所需时间不及轻触式的八达通系统短。香港曾有一些专线小巴、邨巴使用Mondex系统，及后陆续被八达通所取代。

在1996年买下Mondex后，万事达国际组织放弃了本身开发的Mastercard Cash电子收费系统。然而，随着科技的进步，传统的Mondex接触式电子现金业务已过时，取而代之的是非接触式电子现金业务。在台湾，万事达国际组织重新将非接触式电子现金业务命名为Mastercard Cash。

Mondex is a smart card electronic cash system, implemented as a Stored-value card. Conceived by Tim Jones and Graham Higgins of the National Westminster Bank (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.