Thin films of iron pyrite and iron marcasite have been successfully prepared by low pressure chemical vapor deposition (LPCVD) from iron pentacarbonyl (Fe(CO) 5) and tert-butyl disulfide (TBDS) over a wide temperature range from 200 to 500°C. A series of thin film deposition reactions were studied using Fe(CO) 5 and different sulfur sources (H 2S, tert-butyl sulfide, or tert-butyl disulfide). It was found that thin film iron marcasite could be prepared from Fe(CO) 5 and tert-butyl disulfide (TBDS) at a deposition temperature of 200°C. Thin film growth rates greater than 10μ/h could be obtained over surfaces of more than 600 cm 2. Thin film iron pyrite could be prepared at deposition temperatures of 480°C or higher. Thin film growth rates greater than 3 μm/h could be obtained over surfaces of 300 cm 2. By modifying the growth temperatures, various phases of thin film FeS 2 (pyrite, marcasite, and a mixture of pyrite and marcasite) were successfully prepared.