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Carbonization of pure MnO 2 by CH 4 -H 2 gas mixture with various CH 4 /(CH 4 + H 2 ) molar ratios in the temperature range of 900–1250 °C had been performed in our previous work. This study further investigated the carbonization and alloying process of MnO 2 by CH 4 -H 2 gas mixture in the presence of Fe 2 O 3 at 900–1300 °C using XRD, optical microstructure, SEM-EDS and phase diagram analyses. Carbonization test of pure Fe 2 O 3 was also conducted to understand the effect of Fe 2 O 3 on the carbonization of MnO 2 more explicitly. It was found that Fe 2 O 3 could be carbonized to Fe 3 C at 900–1150 °C. The Fe 2 O 3 briquettes began to melt at 1100 °C and a large amount of Fe-C melts appeared as the temperature went up to 1150 °C. When the MnO 2 + 25 wt%Fe 2 O 3 briquettes were reduced at 900–1000 °C in CH 4 -H 2 gas mixture, the Fe 2 O 3 was preferentially carbonized to Fe-C phase while the MnO 2 was only reduced to MnO. The formation of Fe-C phase was beneficial to the carbonization of MnO since the carbonization temperature of MnO can decrease from 1100 °C to 1000 °C. The carbonization degree of MnO was dramatically accelerated over 1100 °C due to the transformation of Fe-C phase from solid state to melts. Morphology analysis indicated that the MnO core was wrapped by the shell of Fe-C melts. The alloying process of Mn-Fe-C was conducted through the elements migration of Fe and Mn between the core and shell. At 1300 °C, the Mn-Fe-C alloy turned to melt and aggregated since the highest melting temperature of the Mn-C-25 wt% Fe system was only 1274 °C. Finally, a ferromanganese crude alloy with 68–72 wt% Mn, 20–25 wt% Fe and 6.0–8.0 wt% C was obtained when the MnO 2 + 25 wt% Fe 2 O 3 briquettes were carbonized by CH 4 -H 2 gas mixture at 1300 °C for 60 min. [ABSTRACT FROM AUTHOR]