This work aims to study the growth and physicochemical properties of second-order nonlinear optical active inorganic crystal of cadmium iodate (CDI). Efforts have been made to grow an improved size single crystal of CDI by the slow-cooling technique. The XRD data of CDI are determined by single-crystal XRD analysis. CDI is further characterized by UV-vis-NIR spectroscopy, TGA, dielectric, ac conductivity, SEM and Vickers hardness studies. The second harmonic generation (SHG) of the sample is demonstrated by the Kurtz and Perry method using Nd:YAG laser and the results confirm that the grown crystal is roughly 6 times more efficient than KDR The ac conductivity (sigma(ac)) of the grown crystal is measured in the frequency range 100 Hz-5 MHz and its temperature dependence is investigated. The estimated Vickers hardness number and work hardening coefficient of CDI ascertains the hard nature of the crystal. (C) 2008 Elsevier B.V. All rights reserved.