Vanadium acetylacetonate, or V(acac)(3), provides a model chemistry for investigating the performance of non aqueous disproportionation flow batteries. A flow reactor was developed to implement studies of efficiency, energy capacity, and power capability with respect to electrolyte flow rate and current density. Reactors incorporating a porous separator allowed V(acac)(3) to be cycled without appreciable capacity fade at current densities up to 100 rnAcm(-2). Experiments at the lowest flow rate, 12.5 mLmin(-1), revealed limitations imposed by residence time within the reactor, which manifested as high charging overpotentials. These overpotentials vanish above 25 mLmin(-1). A higher flow rate of 50 mLmin(-1) yielded performance similar to cells at 25 mLmin(-1), but could improve performance at current densities above 100 mAcm(-2). Extrapolation of power density's dependence on current suggests a maximum power of 0.22 Wcm(-2) for cells run at 206 mAcm(-2). Energy efficiency passes through a maximum of 71% at 40 mAcm(-2) and the corresponding energy density suggests that the chemistry can, in principle, deliver above 13 WhL(-1) in acetonitrile solutions and above 24 WhL(-1) in mixed solvent solutions with higher V(acac)(3) solubility. A V(acac)(3) cell run at 40 mAcm(-2) is shown to exhibit stable capacity and performance for more than 150 cycles.