Milligram quantities of tin (II) can be titrated with iodine generated electrolytically in a solution of hydrochloric acid and potassium iodide. A means has been devised by which the low-level amounts of tin can be reduced to the divalent state prior to titration by passing through a heated antimony reductor column directly into the titration cell. The reduction step is accomplished in 10 min, thus affording a decrease in time over previous methods. The procedure has been applied to the determination of tin in Zircaloy, and the weighted standard deviation of 70 analyses was 0.007 mg of tin. Recovery studies made on two alloys and the statistical analysis of a factorial design experiment employing the determination of tin in synthetic Zircaloy solutions with various combinations of nickel, chromium, and iron show that the three metals do not interfere with the determination of tin in Zircaloy.