This work involves the study of scan rate (10 and 100 mV s(-1)) on electrosynthesis of multi-walled carbon nanotubes/Prussian blue (MWCNTs/PB) thin films using cyclic voltammetry in K-3[Fe(CN)(6)] medium. A heterogeneous reaction between the electrolyte and iron species present in the MWCNT led to the formation of PB in the MWCNT. It was observed that the size of PB cubes is strongly influenced by scan rate, with the formation of structures varying from 50 to 400 nm. The MWCNT/PB films were characterized by different spectroscopic, microscopic and electrochemical techniques that exhibit high electrochemical stability and fast redox process. The films synthesized at a scan rate of 100 mV s(-1) showed better performance for the detection of sulfamethoxazole, due to the smaller size of PB, providing a better interaction between PB and MWCNT.