The optical absorption of as-prepared and thermally annealed As24.5Te71Cd4.5 thin films was measured. The optical energy gap Eo increased from 0.58 to 0.85 eV with increasing thickness of the as-prepared films from 58 to 125 nm. Films annealed at temperatures higher than 423 K showed a decrease in Eo. The electrical conductivity of the as-prepared and annealed films was measured in the temperature range 80–300 K. An amorphous-crystalline transformation was observed after annealing at temperatures higher than 423 K. The results obtained are discussed on the basis of amorphous-crystalline transformations