Thin films of Al-Sb of varying compositions and thickness have been formed on glass substrates employing three-temperature method. Electrical resistivity (ρ) and activation energy (ΔE) have been studied as a function of composition, thickness (d) and temperature of the film. Films of Al-Sb system with aluminium < 50 at.%, ∼ 50 at.% and > 50 at.% exhibit metallic, semiconducting and metallic to semiconducting behaviours respectively. Activation energy (ΔE) of semiconducting films found to vary inversely with thickness, is attributed to combined effects of change in barrier height due to the size of grains and stoichiometry in the films.