Nanocrystalline　β-In2S3　was　prepared　by　reacting　In(NO3)3　with　thioacetamide　through　hydrothermal　method　at　120°C　for　12 h.　The　size　and　morphology　of　In2S3　photocatalyst　were　characterized　using　X-ray　diffraction　(XRD),　scanning　electron　microscope　(SEM),　transmission　electron　microscopy　(TEM),　and　Brunauer–Emmett–Teller　(BET)　surface　area　analysis.　The　band　gap　energy　was　measured　using　Kulbeka–Munk　function　and　the　electronic　state　of　the　prepared　In2S3　was　determined　by　X-ray　photoelectron　spectroscopy.　The　photocatalytic　activity　of　the　prepared　sample　was　investigated　by　the　photocatalytic　degradation　with　20 mg/L　of　the　tetracycline　(TC)　under　natural　sunlight　as　a　source　of　irradiation.　The　results　showed　that　the　synthesized　In2S3　matches　completely　with　the　cubic　phase　of　β-In2S3　with　a　surface　area　of　95.6726 m2 g−1,　and　the　photocatalytic　activity　for　the　degradation　of　TC　under　natural　sunlight　irradiation　was　excellent　followed　with　first-order　kinetics　and　the　complete　removal　could　be　within　30 min,　which　suggests　that　the　prepared　photocatalyst　has　the　potential　to　degrade　the　antibiotics.　©　2015　Balaban　Desalination　Publications.　All　rights　reserved.