Preparation of polycrystalline mercuric iodide very thin (1 mu m) films using laser ablation and thick films (100-600 mu m), using hot pressing, hot wall vapor deposition and screen printing methods, fabricated as radiation detector plates are briefly described. X-ray diffraction, photoluminescence and optical microscopic measurements as well as response to nuclear radiation will be given. Finally, recent results obtained with a large area imaging pixel detector will be shown.