A microwave digestion system is indispensable for the acid digestion of materials to be analyzed with (multi-collector) ICP-mass spectrometry (geological materials, plant material, biological tissues, etc). For enabling full digestion of the samples and reducing the risk of contamination and analyte losses, sophisticated instrumentation is required, allowing rapid digestion in a closed vessel and offering the possibility of temperature and pressure controm and adjustment of the power via a feedback mechanism when required.