We have developed a procedure to purify, synthesize and grow InI single crystals using the Bridgman technique. The commercial product of InI from Alfa Aesar (99.998% InI or 4 N) was zone refined by 50 passes of a zone-heater at 420 °C, traveling at 2 cm/h (the melting point of InI is 360 °C). InI was also synthesized using high purity In and I2 by vapor transport technique. The grown InI single crystal showed a clear band edge excitonic emission around 2.02 eV at 6 K using photoluminescence measurement. The resistivities of InI detectors were found to be ∼2×109 and 1×108 Ω cm for zone refined and vapor synthesized starting materials, respectively. The InI detector formed by Pd–Pd contact showed clear peak of alpha particle detection at room temperature using 241Am source.