In the last decade, there has been a growing public and scientific concern regarding the occurrence and potential harmful effects of chemicals of emerging concern (CECs) in the aquatic environment. However, little attention has been paid so far to their prevalence and quantification in marine ecosystems. To study and evaluate the fate, effects, and environmental and human risks posed by these emerging contaminants, information regarding their presence in marine waters and organisms is urgently needed. Therefore, the research within this doctoral thesis aimed at the determination of different groups of CECs, including pharmaceuticals, perfluorinated compounds (PFCs) and pesticides, in environmental matrices. To this end, new analytical methods employing modern and sophisticated equipment were developed, validated and applied to samples originating from the Belgian coastal zone.