A token handling device transmits, using an electro-magnetic carrier, data, clock pulses and power to a token. The token transmits data by varying the degree of absorption of the carrier in synchronism with the clock pulses. These data transmissions are detected by a receiver in the token handling device, the sensitivity of which is adjusted each time a token is received. The token could be used in transactions in place of coins, or alternatively could be used for identification purposes in other areas. Data stored by the token could be used to change the way in which the token handling device operates. The token handling device may for example form a vending machine, and the token could be used to alter the pricing of goods vended thereby.; The token handling device may be combined with a coin validator, in which case there is preferably a common path from an entrance slot for carrying both the tokens and the coins to appropriate testing apparatus.