1 1 1 In was produced by the 1 0 9 Ag(α, 2n) 1 1 1 In reaction. A simple radiochemical separation technique, using Dowex-50 cation exchange resin (with prior removal of copper bulk, if present), has been employed to separate radioindium from inactive contaminants like Ag, Cu, Fe and active contaminant like 6 7 Ga and 6 5 Zn. The radiochemical separation yield was 90-99%. The radionuclidic purity of 1 1 1 In was >99% at 60 h after EOB. The level of all the inactive contaminants was < 5 μg/mL in the final product.