Cadmium zinc telluride (CdZnTe) detectors are potential replacements for traditional room temperature detectors, such as silicon (Si), in many applications. CdZnTe has been considered as a promising semiconductor material for hard X‐ray and ‐ray detection because the stopping power of CdZnTe is better than traditional materials. To exploit them for practical applications, their behaviour under harsh conditions must be fully characterised and understood. In this study, the electrical characteristics of the CdZnTe three‐dimensional (3D) detector are comprehensively studied through TCAD simulations. The very low leakage current, which is about 5.5 pA at 200 V, allows applying higher bias voltages than possible with traditional two‐dimensional (2D) detectors. Moreover, the effect of the temperature on the leakage current is studied. Additionally, the collection time is found to be about 2 ns and the amplitude of the current is 0.8 nA at 200 V. The obtained results prove the applicability of the CdZnTe 3D detector under various operating conditions.