Abstract: A novel electrochemical sensor for the detection of formaldehyde is prepared based on electrodepositing palladium nanoparticles on the Nafion film coated glassy carbon electrode(Pd/Nf/GCE) through cyclic voltammetry(CV).Electrocatalytical behaviors of the modified electrode are investigated by cyclic voltammetry and differential pulse voltammetry(DPV).Experimental conditions are optimized and a voltammetric method for determining formaldehyde is developed.Experimental results show that the electrode displays a remarked electrocatalytic activity in alkaline solution and exhibits a linear response to formaldehyde in the range of 5.0 μmol/L~5.0 mmol/L.The linear regression equation is i_p=7.69+2.22×10⁴c with a correlation coefficient of 0.996 7 and the detection limit is estimated to be 1.0 μmol/L calculated from the signal-to-noise ratio of 3∶1.The presented methods of determining formaldehyde exhibit good reproducibility and recovery.