Humic substances are in the focus of many specialists representing different disciplines, including chemists and scientists from soil, coal, freshwater, and marine sciences. The mutual interaction of humic substances with heavy metals, pesticides, PAHs, micro- and nano-plastics, antibiotics and other xenobiotics is one of the most important aspects of their accumulation and translocation in contaminated and uncontaminated environmental compartments. These general considerations render this interdisciplinary topic extremely important for environmental pollution. Fate and activity of xenobiotics depend on their interaction with organic matter and specific humic fractions that may influence their bioavailability in soil due to various interactions with these substances. At the same time, they may affect the properties of humic substances, playing a crucial role in several processes determining quality of the terrestrial and aquatic systems. The session will cover various aspects of mutual interaction between humic substances and a broad spectra of xenobiotics and will provide deeper insights and understanding of their behavior mechanisms in relation to humic substances, that occurs naturally in the environment.