We present a model of a two-step solar process for producing Zn from ZnO. The process consists of the following reactions: Fe3O4(l) --> 3FeO(l) + 1/2 O-2, and 3FeO(s,l) + ZnO(s) --> Fe3O4(s) + Zn(g). The rate and extent of decomposition of the first reaction is limited by the rate at which O-2 diffuses from the liquid-gas interface. We verified experimentally that the second reaction is possible. A theoretical study shows that the Zn yield can be controlled by temperature, pressure, and partial pressure of Zn. The maximum overall efficiency of this two-step process varies from 14 to 64% in the temperature range of 2100-2200 K.