Thin films of bismuth sulfide (Bi2S3) were grown by two deposition techniques, by thermal evaporation and by chemical deposition. The thermally deposited reactions consisted in depositing the individual elements, namely bismuth and sulfur, sequentially from a tungsten boat source and allowing the layers to interdiffuse to form the compound during the heat-treatment. The chemical deposition was based on the reaction between the triethanolamine compex of Bi3+ ions and thiourea in basic media. Scanning electron microscope and X-ray diffraction analysis were made on as-deposited and on annealed films to determine their structure. The different electronic transitions and the optical constants are determined from the transmision and reflection data of these thin films for normal incidence. The optical gaps of Bi2S3 films show a remarkable dependence on the preparation method.Tanki su slojevi bismut sulfida (Bi2S3) načinjeni dvjema metodama, vakuumskim naparavanjem i kemijskim taloženjem. Ti su se slojevi istraživali sustavno-pretražnom elektronskom mikroskopijom i difrakcijom rentgenskog zračenja, prije i nakon termičkog opuštanja. Našao se je niz elektronskih prijelaza i odredile se optičke konstante na osnovi transmisijskih i refleksijskih podataka za okomitu upadnu svjetlost. Optički procijepi Bi2S3 pokazuju priličnu ovisnost o metodi pripremanja
