In Tenerife the current used is 220 Volts AC 50Hz, which is the same all over the Canaries. Plugs have two pins, identical to the European mainland.
If you are travelling from the UK, it may be a good idea to bring a plug adaptor with you. But do not worry if you forget, as they are readily available in shops all over the island.
Visitors from the USA will also need a voltage converter.