Abstract Electrochemically active composite film containing multiwalled carbon nanotubes (MWCNTs) and vitamin B(12) was synthesized on glassy carbon, gold, and indium tin oxide electrodes by the potentiodynamic method. The presence of MWCNTs in the composite film (MWCNT-B(12)) modified electrode mediates vitamin B(12)'s redox reaction, whereas vitamin B(12)'s redox reaction does not occur at bare electrode. The electrochemical impedance spectroscopy studies reveal that MWCNTs present in MWCNT-B(12) film enhance electron shuttling between the reactant and electrode surface. The surface morphology of bare electrode, MWCNT film. and MWCNT-B(12) composite film was studied using atomic force microscopy, which reveals vitamin B(12) incorporated with MWCNTs. The MWCNT-B(12) composite film exhibits promising enhanced electrocatalysis toward hydrazine. The electrocatalysis response of hydrazine at MWCNT film and MWCNT-B(12) composite film was measured using cyclic voltammetry and amperometric current-time (i-t) curve techniques. The linear concentration range of hydrazine obtained at MWCNT-B(12) composite film using the i-t curve technique is 2.0 0204M-1.95 mM. Similarly, the sensitivity of MWCNT-B(12) composite film for hydrazine determination using the i-t curve technique is 1.32 mA mM(-1)cm(-2), and the hydrazine's limit of detection at MWCNT-B(12) composite film is 0.7 0204M.