The electrochemical reaction of Sn(II)/Sn was investigated in a room-temperature ionic liquid, 1-n-butyl-1 -methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMPTFSI) at 25 degrees C. The anodic dissolution of Sn metal proceeded by a two-electron transfer reaction with a current efficiency of nearly 100%. Electrodeposition of Sn on a Cu substrate is possible in BMPTFSl containing Sn(II). The formal potential of the Sn(II)/Sn is -0.57 V vs. Ag/Ag(I). The diffusion coefficient of Sn(II) was estimated to be similar to 1 x 10(-7) cm(2) s(-1) from chromoamperometric and chronopotentiometric techniques. The initial stage of nucleation of Sn on a polycrystalline Pt substrate was found to be classified into a three-dimensional progressive nucleation under diffusion control by chronoamperometry, suggesting the rate of nucleation is faster than that of crystal growth. (C) 2008 Elsevier Ltd. All rights reserved.