The study of interfacial electron transfer (ET) reaction between ferricinium (Fc+) produced in situ in 1,2-dichloroethane (DCE) and ferrocyanide in ice matrix under low temperatures by the scanning electrochemical microscopy (SECM) is reported. Tetrabutylammonium (TBA+) is used as the common ion (potential-determining ion) in both phases to control the interfacial potential difference. The potential drop across the liquid/liquid interface can be quantitatively adjusted by changing the ratio of concentra-tions of TBA+ between the two phases. The apparent hetero-geneous rate constants for Fc+ reduction by -46Fe(CN) at the interface under different temperatures have been ob-tained by a best-fit analysis, where the experimental ap-proach curves are fitted to the theoretical simulated curves. A sharp change has been observed for heterogeneous rate constants around the freezing point of the aqueous phase, which reflects the phase transition process. The study of interfacial electron transfer (ET) reaction between ferricinium (Fc +) produced in situ in 1,2-dichloroethane (DCE) and ferrocyanide in ice matrix under low temperatures by the scanning electrochemical microscopy (SECM) is reported. Tetrabutylammonium (TBA + is used as the common ion (potential-determining ion) in both phases to control the interfacial potential difference. The potential drop across the liquid / liquid interface can be quantitatively adjusted by changing the ratio of concentra tions of TBA + between the two phases. The apparent hetero-geneous rate constants for Fc + reduction by -46Fe (CN) at the interface under different temperatures have been ob-tained by a best-fit analysis, where the experimental ap-proach curves are fitted to the theoretical simulated curves. A sharp change has been observed for heterogeneous rate constants around the freezing point of the aqueous phase, which reflects the phase transition process.