Abstract Highly dispersed isolated single-walled carbon nanotubes (SWNT) on gold electrode were prepared to study the effect of electrochemical doping on their Raman features. Spectrum of the radial breathing mode of SWNT was dependent upon the electrode potential. Change in the intensity of the spectrum was reversible. Distinct difference in the potential dependence was observed at SWNT with different diameter. Linewidth of the spectrum also showed potential dependence at the metallic tubes. Characteristics of the spectral changes induced by electrochemical doping were correlated to the difference in electronic density of individual SWNT.