Tungsten halogen lamps behave in a similar manner to other incandescent lamps when run on a different voltage. A 300 watt tubular halogen bulb operated at full power quickly reaches a temperature of about 540°C (1,004°F), while a 500 watt regular incandescent bulb operates at only 180°C (356°F) and a 75 watt regular incandescent at only 130°C (266°F). More recently, wider beam versions have become available designed for direct use on supply voltages of 120 or 230 V.

For a fixed power and life, the luminous efficacy of all incandescent lamps is greatest at a particular design voltage. The presence of the halogen, however, sets up a reversible chemical reaction cycle with this evaporated tungsten. The first lamps used only tungsten for filament supports, but some designs use molybdenum – an example being the molybdenum shield in the H4 twin filament headlight for the European Asymmetric Passing Beam. Since quartz is very strong, the gas pressure can be higher, [14] which reduces the rate of evaporation of the filament, permitting it to run a higher temperature (and so luminous efficacy) for the same average life.

Regeneration of the filament is also possible with fluorine, but its chemical reactivity is so great that other parts of the lamp are attacked. Halogen lamps made for 12 to 24 volt operation have good light outputs, and the very compact filaments are particularly beneficial for optical control (see picture).

Incandescent lamp variety A halogen lamp operating in its fitting with the protecting glass removed A halogen lamp behind a round UV filter. Quartz iodine lamps, using elemental iodine, were the first commercial halogen lamps launched by GE in 1959.The tungsten released in hotter regions does not generally redeposit where it came from, so the hotter parts of the filament eventually thin out and fail.

In ordinary incandescent lamps, evaporated tungsten mostly deposits onto the inner surface of the bulb, causing the bulb to blacken and the filament to grow increasingly weak until it eventually breaks.The halogen cycle keeps the bulb clean and causes the light output to remain almost constant throughout the bulb's life. A carbon filament lamp using chlorine to prevent darkening of the envelope was patented [2] in 1882, and chlorine-filled "NoVak" lamps were marketed in 1892. This allows the filament to operate at a higher temperature than a standard incandescent lamp of similar power and operating life; this also produces light with higher luminous efficacy and color temperature.

Australia banned some halogen light bulbs above 10W from September 2021,replaced by eco halogen, [7] Later than the planned date of September 2020 [8] to keep the policy in line with the European Union. The production and importation of directional mains-voltage halogen bulbs was banned on 1 September 2016 and non-directional halogen bulbs followed on 1 September 2018.The bulb must be made of fused silica (quartz) or a high-melting-point glass (such as aluminosilicate glass).