Abstract Amorphous films (240–1740 Å thick) of gallium antimonide were formed by vacuum evaporation onto goldseal glass slides and onto sodium chloride crystals. They were annealed in successive cycles to obtain the ideal amorphous state. The heat treatment was continued until the crystalline phase was obtained. The electrical conductivity, the thermoelectric power with respect to bulk silver and the optical absorption were measured in all these films before and after crystallization. The electron diffraction patterns of the as-deposited, the annealed and the crystalline films were obtained using a transmission electron microscope. The activation energy for conduction Δ E, the amorphous-to-crystalline transition temperature, the density of states at the Fermi level N( E F) and the optical energy gap E o were evaluated.