A theoretical and experimental investigation is reported into the influence of hydrogen heat treatment on the electrical and electroluminescent characteristics of GaP LEDs. It is shown that electrical transport in processed specimens is mainly by tunneling. The tunneling rate as a function of some properties is examined. A mechanism of electrical transport in the LEDs is proposed. The role of hopping conduction is discussed, and its parameters are determined. Electroluminescence spectra are measured and explained in terms of thermally induced structural changes in defects.