The sensitive character of tin oxidation and the effect of pH on the solubility of tin species highlight several challenges for further understanding tin speciation within aqueous solutions. Raman spectroscopic monitoring of aqueous stannous chloride solutions over a broad pH range resulted in the observation of several insoluble tin species (e.g. abhurite and hydroromarchite) suspended within the neutral and alkaline solutions. An aqueous tin speciation mechanism was proposed based on semi-quantitative indirect hard modeling analysis of these solutions. The methods employed in this study demonstrate the usefulness of Raman spectroscopy for the characterization of complex heterogeneous mixtures. Copyright © 2012 John Wiley & Sons, Ltd.