Iodine is a microelement which occurs in natural water in different concentrations dependent on water type, origin and total dissolved solids concentration. The objects of research were natural geothermal water. In this paper, the fitness of the inductively coupled plasma mass spectrometry (ICP-MS) method for iodine determination in water with higher temperatures was tested and selected methodological problems were discussed. Basic method parameters (precision, accuracy, linearity, uncertainty) were determined. Calculated statistical parameters of the validated method fulfil the assumed criteria. The received results (correlation coefficient equal to 0.999) show that the linearity of the ICP-MS method is good. The accuracy was expressed as recovery (R) and according to the literature is at an acceptable level. The results of precision assessments (RSD) also correspond to the literature data.