The standard electricity supply is 220 – 240 volt AC. The power supply on the mainland and Zanzibar can sometimes be unreliable.
Most hotels have back-up generators. In the parks most lodges and camps do not have mains electricity but have generators. Some have very limited power relying on solar power and kerosene lamps at night, which is quite romantic. Plugs at hotels vary, and even within different parts of the same hotel they can vary.
In the main they are the 3 square pin plugs similar to the UK, but it is advisable to take a multi-adaptor.