Reactive thermally evaporated transparent conducting indium tin oxide (ITO) layers are used as window material and for current spreading layers on AlCaInP light emitting diodes (LEDs). The sheet resistance of the ITO films deposited is of the order of 4.5 Omega/rectangle with up to 90% transmission in the visible region of the spectrum. In all cases, the der ices incorporating the ITO layer gave a marginally greater output (10%) than the standard non-ITO devices.