To characterize the effective temperature of electrochemical reactions under the condition with a heated working electrode and ambient recirculating electrolyte, we measured the open circuit potential with an electrolyte containing equal concentrations of potassium ferri/ferrocyanide, whose temperature-dependent equilibrium potential is well established. We performed open circuit voltage (OCV) measurements at our standard flow rate of 150 µL/s as well as a reduced flow rate (Figure ). While the observed temperatures reflect the expectation that rapidly flowing ambient electrolyte lowers the effective reaction temperature with respect to the electrode temperature, these deviations are within ca. 5 °C (Figure , Table , Figure ) and demonstrate our ability to systematically vary with reaction temperature via electrode heating. To further understand the differences between surface and bulk heating, we identified the mass transport limited current for each heating system by performing constant potential electrolyses at variable temperatures and using Fick's second law to determine the average concentration boundary layer (δC) thickness (Figure ). Upon changing the temperature, we find that the δC decreases in thickness for both systems, but marginally less with SH, which we expect is due to incomplete/inhomogeneous heating of the concentration boundary layer with SH (Figure ). Partial heating is consistent also with the changes in cell resistance since we observe slightly lower resistances with BH than SH.