In this paper, pig iron production by microwave heating is experimentally investigated. In order to explore possible effects of the microwave frequency, identical mixtures of magnetite and carbon powder were processed in different microwave systems operating at 2.45 GHz and 30 GHz, respectively. The weight ratio of magnetite and carbon in the powder mixture was 89:11 weight%. According to the corresponding chemical equation, this should allow to produce pig iron that includes 2 weight% of carbon. High-quality pig iron was obtained in the 30 GHz heating system in air. At 2.45 GHz heating in nitrogen gas, pig iron was obtained. However, under similar conditions of 30 GHz heating system in air, FeO was mainly obtained. This result suggests that the chemical reduction of magnetite is more efficient at higher microwave frequencies.