Surfactant modified carbon nanotube paste electrode is prepared as electrochemical sensor with high sensitivity responding to mitoxantrone (MTX). Electrochemical oxidation of MTX is investigated in buffered solution by cyclic voltammetry that is found very sensitive method for detection of MTX. It is shown that the sodium dodecyl sulfate modified carbon nanotube paste electrode (SDSMCNTPE) gives enhanced current response for MTX compared to the bare carbon nanotube paste electrode (BCNTPE). Different parameters were tested to optimize the conditions for MTX determination. The effects of different surfactant and surfactant concentration, pH, scan rate, and concentration of MTX on the oxidation peak current values were determined. Excellent results were obtained by cyclic voltammetry using SDSMCNTPE, where two MTX oxidation peaks appeared around 370 and 600 mV vs. SCE. Detailed analysis of the second voltammetric peak showed the linear dependence on concentration between 2×10−7 and 7×10−6 M MTX with the slope of the corelation coefficient of 0.99271. LOD and LOQ were determined as 3.5 ×10−8 M and 11×10−8 M, respectively. The SDSMCNTPE showed very good reproducibility, high stability in its voltammetric response, high electrochemical sensitivity and low detection limit for MTX.