A sealed, metal oxide, electrodeless discharge lamp having a high emissionntensity in the visible 400-700 nm range. Within the sealed container assembly of the lamp there is a source of metal atoms capable of forming a volatile oxide and a source of an oxygen containing gas. The lamp produces a plasma and volatilizes the metal into the plasma. Preferably the lamp is at a low pressure of about 20-40 torr and the metals are molybdenum or tungsten. Power is applied by inductively coupled electromagnetic radiation. A regenerative agent such as a halogen is added for recycling any deposited metal into the gas phase and to form a volatile compound with the source of metal atoms. The agent lowers the temperatures needed to volatilize the metal into the plasma. The lamp is operated by first providing energy at a low level to initiate the plasma and then supplying the metal atoms into the plasma.