A silver indium sulfide (AgInS2) epilayer was grown by hot wall epitaxy method, which has not been reported in the literature. The grown AgInS2 epilayer was found to be a chalcopyrite structure and evaluated to be high quality crystal. From the photocurrent measurement in the temperature range from 30 to 300 K, two peaks of A and B were only observed, whereas three peaks of A, B, and C were seen in the PC spectrum of 10 K. These peaks are ascribed to the hand-to-hand transition. The valence band splitting of AgInS2 was investigated by means of the photocurrent measurement. The crystal field splitting, Delta(cr), and the spin orbit splitting, Delta(so), have been obtained to be 0.150 and 0.009 eV at 10 K, respectively. And the energy band gap at room temperature has been determined to be 1.868 eV. Also, the temperature dependence of the energy band gap, E-g(T), was determined. (C) 2002 Elsevier Science B.V. All rights reserved.