The signal response of a twin platinum probe scanning reference electrode, when scanned across a localized electrochemical event, has been mathematically modeled. The model suggests that the key parameters that affect the signal response are the charge-transfer resistance (R-ct) and double-layer capacitance (C-dl) of the platinum electrodes, the input impedance of the measuring device (R-m), and the scan time across the event. The phenomenon of "signal shadowing," i.e., the appearance of cathodic artefacts following real anodes and vice verse, has previously been explained as a geometrical effect of the probe configuration. Results presented as part of this work, however, suggest that the major contribution to shadowing is derived from the electrical response of the measurement circuit. Optimization of the equipment parameters indicates that a more accurate and precise representation of local electrochemical activity can be obtained by increasing the R-m/R-ct ratio and/or scan speed. Model predictions of the probe response correlated well with real scans performed across a simulated localized event.