Indirect carbothermal reduction of alumina for the production of aluminum utilizes different reducing agents to convert alumina into intermediate aluminum compounds. In the present study, the carbosulfidation route for aluminum production utilizing H2S(g) as the reductant and sulfur source has been investigated, in particular the formation of AhS3 in the first step of the process. The results of the thermodynamic analysis predicted that conversion of Ah03(S) to AhS3(l) significantly increases above 1400°C at 1 atmosphere pressure. Experimental investigations were carried out at temperatures of 1100 to 1500°C using dilute H2S(g) gas in argon. The reaction products were analyzed using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), inductively-coupled plasma absorption emission spectroscopy (ICP-AES) and chemical filtration. The X-ray diffraction results confirmed the presence of AhS3(S). Percentage of conversion from Ah03 to AhS3 was found to be over 80% at 1500°C.