Mercuric iodide platelets were grown in the HgI2-HI-H2O system by solvent evaporation at constant temperature. Different solution temperatures, growing times and stirring conditions were studied. In order to determine the best growing parameters the chemistry of the HgI2-HI-H2O system was studied. Complexes [HgI3](-) and [HgI4](-2) were identified and quantified in the solution by visible and UV spectrometry, according to the R ratio ([HgI2]/[HI]). Solution oxidation and I-3(-) interference were eliminated performing growth in high purity Argon atmosphere. Good mercuric iodide platelets, up to 6.0 x 7.0 x 1.5 mm(3) in size, were obtained with appropriate argon flow, temperature and growing time, for several independent experiences. Platelets were observed by optical microscopy and the absence of possible dislocations was confirmed by studying etch pits density after etching with ethanol-trichloroethylene. Nonexistence of occluded water and hydrocarbons was confirmed by Fourier transform infrared spectroscopy and was related to results obtained for mercuric iodide crystals grown by the physical vapor transport method. Detectors were made with the platelets and their apparent resistivity, current density and X-ray performance were measured. Discussions about future improvements of growing mercuric iodide platelets in the HgI2-HI-H2O system and comparison of this method with others are included.