Single crystals of pure and thallium (T1) doped cesium iodide (CsI) have been grown by melt growth (Bridgman) technique. The grown crystals were subjected to powder X-ray diffraction and high-resolution XRD analysis. The cut and polished crystals were characterized for luminescence studies. UV-visible transmission studies have been carried out on the grown crystal in the wavelength range 200-650 nm. From the transmission spectrum it was found that the cut off wavelength increases with increase in T1 concentration and the transmittance is about 70%. The 0.06 mol% of T1 doped CsI crystal shows a good energy resolution of 7.6%. The hardness decreases for increasing the doping concentration. Etching studies have been carried out on doped and undoped crystals using methanol and water as etchant. (c) 2005 Published by Elsevier B.V.