The influence of thin-layer resistance in cyclic voltammetry was studied in detail. Under the experimental conditions, a linear relationship between the peak-peak potential difference and the product of the peak current and the resistance was obtained and can be used to determine the thin-layer solution resistance. A non-linear least-squares analysis was used to process the data and an empirical equation of the peak-peak potential difference (Delta E(p)) related to the ideal peak current (I-p(0)) and the thin-layer resistance (r(m)) was obtained as Delta E(p) = (5.931RT/F) ln(0.1400Ip(0)r(m)(F/RT) + 0.9819).