The orientation dependence of the visible-light stimulated photochemical reduction of aqueous Ag+ on polycrystalline hematite Fe2O3 was determined by observing the relative amount of reduced Ag-0 on crystals of known surface orientation over all possible orientations. The results show that surfaces oriented within 20 degrees of the ( 1102) plane are the most active and surfaces close to the ( 0001) plane are the least active. A strong correlation is observed between the orientation-dependent activity and the orientation-dependent surface potential measured by scanning Kelvin probe force microscopy. Surfaces near the most active ( 1102) plane and the least active ( 0001) plane are, respectively, at the most positive and the least positive ends of the potential range among all grains. The trends in activity are concluded to arise from a combination of internal fields associated with surface charges and bulk transport effects.