Dissolved Fe(II) is produced as a result of microbial reduction of solid Fe(III) minerals in anoxic soil environments. It is well known that dissolved Fe(II) can serve as an important reductant of naturally occurring oxidants such as oxygen and Mn(III,IV) oxides and contaminants such as chromate. Recently, we showed that dissolved Fe(II) can reduce dissolved Cu(II) to Cu(I) in a rapid reaction. Here, we employ an ultraviolet-visible stopped-flow technique to measure the kinetics and mechanism of Cu(II) reduction by Fe(II) in aqueous solutions by monitoring production of the Cu(I)-bathocuproine complex at 483 nm. Reactions were performed over environmentally relevant ranges of reactant concentrations, pH, and temperature. There was a first order dependence on both Fe(II) and Cu(II) concentrations. The initial rate of Cu(I) production increased twelve-fold as pH increased from 3.6 to 5.5. This may be due to the role of hydrolyzed Fe(II) as a reactive intermediate aqueous species. In addition, there was an eight-fold increase in the rate of Cu(I) production as temperature increased from 5 degrees to 45 degrees Celsius. The temperature data will be fit to the Arrhenius and Eyring equations to assist in determination of the rate limiting step for the reaction. This process may be important in Fe(III)-reducing environments where dissolved Fe(II) accumulates and reacts with Cu(II) derived from natural or anthropogenic sources.