In this present study, single-walled carbon nanotubes (SWCNT) modified disposable pencil graphite electrodes (SWCNT-PGEs) were developed for the electrochemical monitoring of anticancer drug, and its interaction with double stranded DNA (dsDNA). Under this aim, SWCNT-PGEs were applied for the first time in the literature to analyse of 6-Thioguanine (6-TG), and also to investigate its interaction with DNA by voltammetric and impedimetric methods. The surface morphologies of PGE and SWCNT-PGE were explored using scanning electron microscopy (SEM) and electrochemical characterization of unmodified/modified electrodes was performed by cyclic voltammetry (CV). Experimental parameters; such as, the concentration of 6-TG and its interaction time with dsDNA were optimized by using differential pulse voltammetry (DPV). Additionally, the interaction of 6-TG with dsDNA was studied in case of different interaction times by electrochemical impedance spectroscopy (EIS) in contrast to voltammetric results. The detection limit of 6-TG was found to be 0.25 mu M by SWCNT-PGE.