Ion mobility separation (IMS) was hyphenated to high resolution mass spectrometry (HRMS) instruments as an additional separative dimension to chromatography and mass spectrometry. In IMS, ion characteristics such as shape and size are studied by observing their response upon an acceleration in a buffer gas by means of an electric field. The extra physical separation orthogonal to chromatography (often liquid chromatography) and mass spectrometry provides relevant and meaningful information for the enhanced identification of organic micropollutants. Additionally, the utilization of IMS-HRMS instruments for the analysis of organic micropollutants in complex matrices provides, among others, the removal of coeluting interferent substances, the enhancement of signal-to-noise ratio for compounds of interest, or even the reduction of false positive detections. All these as well as other benefits of IMS are discussed in depth along the sections of this chapter. Special attention is also drawn to topics in which further research or hardware improvements are needed. Overall, the role of IMS-HRMS for the analysis of organic micropollutants in environmental samples is examined.