The electrochemical reactions occurring during electrodeposition of nickel from acidic sulfate solutions were examined by cyclic and linear sweep voltammetry techniques. The effect of pyridine, 2-picoline and 4-picoline on the electrode polarization behaviour and electron transfer parameter of the cathodic reduction process was also investigated. Strongest electrode polarization was seen with 4-picoline. The order of cathodic polarization was 4-picoline > 2-picoline > pyridine. Kinetic parameters such as Tafel slope, transfer coefficient and exchange current density were determined to analyse the nature of the electrode reactions. The exchange current density for nickel deposition on nickel and stainless steel substrates was in the order 4-picoline < 2-picoline < pyridine.