The electrodeposition of lanthanum on a Pt electrode was investigated in 0.01 mol/L LaCl3-0.1 mol/L LiCl-EMIMBF4 ionic liquid. The cyclic voltammetry, chronoamperometry and constant voltage electrolysis techniques were employed. The results of the cyclic voltammogram and the XRD pattern of deposits after electrolysis under constant voltage have supported a one step electrodeposition mechanism of lanthanum, La3+ + 3e-→La. The results also indicate that the reduction of La3+ ion is irreversible. The transfer coefficient and the diffusion coefficient of La3+ ion in 0.01 mol/L LaCl3-0.1 mol/L LiCl-EMIMBF4 ionic liquid are 0.0492 and (1.07-1.19)×10-6 cm2/s, respectively