Abstract Mixed ligand complexes of Co(II) with pyridines and halide and pseudohalide have been synthesised. The reduction of synthesised complexes at dropping mercury electrode in various percentage of dimethyl formamide have been studied. The reduction is diffusion controlled. Slope values indicate the reduction to be irreversible. Kinetic parameters ( K s , K o f and α n ) have been calculated by Matsuda and Koutecky's method. K s value was found to be in order 10 −4 cm. The effect of temperature and various composition of dmf have been investigated. At higher temperature the reduction becomes less irreversible.