The influence of solution chemistry on the electrodeposition of Sn from Sn(II)-citrate solutions is studied. The distribution of various Sn(II)-citrate complexes and citrate ligands is calculated and the results presented as speciation diagrams. At a SnCl2 center dot H2O Concentration of 0.22 mol/L and citrate concentration from 0.30 mol/L to 0.66 mol/L, SnH3L* (where L represents the tetravalent citrate ligand) is the main species at pH below about 1.2 and SnHL- is the main species at pH above about 4. Polarization studies and reduction potential calculations show that the Sn(II)-citrate complexes have similar reduction potentials at a given solution composition and pH. However, the Sn(II)-citrate complexes become more difficult to reduce with higher total citrate concentration and higher solution pH. Nevertheless, SnHL- which forms at higher pH is a favored Sn(II)-citrate complex for Sn electrodeposition due to better plated film morphology, likely as a result of its slower electroplating kinetics. Precipitates are formed from the Sn(II)-citrate solutions after adding hydrochloric acid (to lower the pH). Compositional and structural analyses indicate that the precipitates may have the formula Sn2L. (c) 2008 Elsevier Ltd. All rights reserved.