The signal response of a twin platinum probe scanning reference electr
ode, when scanned across a localized electrochemical event, has been m
athematically 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 in
put impedance of the measuring device (R-m), and the scan time across
the event. The phenomenon of ''signal shadowing,'' i.e., the appearanc
e of cathodic artefacts following real anodes and vice verse, has prev
iously been explained as a geometrical effect of the probe configurati
on. Results presented as part of this work, however, suggest that the
major contribution to shadowing is derived from the electrical respons
e of the measurement circuit. Optimization of the equipment parameters
indicates that a more accurate and precise representation of local el
ectrochemical activity can be obtained by increasing the R-m/R-ct rati
o and/or scan speed. Model predictions of the probe response correlate
d well with real scans performed across a simulated localized event.