This project involves the precipitation and stabilisation of colloidal tin (IV) oxide dispersions. Colloidal dispersions of tin (IV) oxide of cassiterite structure were prepared by forced hydrolysis of acidic tin (IV) chloride solutions in the presence and absence of urea. The concentration range of tin (IV) chloride investigated was 0.2-0.0005 mol l-1, at a HC1 concentration of 0.3 mol l-1 and, when used, a [urea]:[SnC14.5H2O] ratio of 50: 1. These conditions resulted in the synthesis of nanometre-sized colloidal dispersions of fairly uniform size and shape.