[en] Present communication deals with study of effect of SHI irradiation of 100 MeV oxygen ions on the electrochemically synthesised polyaniline (PANI)/single walled carbon nanotube (SWNTs) composite electrode. PANI/SWNTs composite was used for the modification of stainless steel electrode. The composite was irradiated with fluences 1 × 10¹⁰ ions cm⁻², 1 × 10¹¹ ions cm⁻² and 1 × 10¹² ions cm⁻² of oxygen ions having energy 100 MeV. Electrochemical techniques viz. cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to study the electroactive nature of composite before and after irradiation. Morphological study was carried out using Field Electron Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM). Composite matrix irradiated with fluence 1 × 10¹⁰ ions cm⁻² had shown good electroactive nature and therefore was used for analytical application viz. electrochemical detection of divalent cobalt ions. The irradiated PANI/SWNTs composite was modified by chelating ligand viz. dimethylglyoxime (DMG) to ensure the selectivity of metal ion viz. Co(II). The electrode (DMG modified SHI irradiated PANI/SWNTs composite) could detect the lowest concentrations to 0.355 μML⁻¹ or 0.1 mgL⁻¹ which is equal to Maximum Contaminant Level (MCL) of cobalt ions proposed by US EPA. The analytical behaviour of electrode has proved the SHI irradiation as suitable tool for modification of organic conducting polymers (OCP)/SWNTs composite. (paper)