Self-assembled monolayers (SAMs) of selenium have emerged into a rapidly developing field of nanotechnology with several promising opportunities in materials chemistry and catalysis. Comparison between sulfur-based self-assembled monolayers and newly developed selenium-based monolayers reveal outstanding complimentary features on surface chemistry and highlighted the key role of the headgroup element. Diverse structural properties and reactivity of organosulfur and organoselenium groups on the surface provide flexible frameworks to create new generations of materials and adaptive catalysts with unprecedented selectivity. Important practical utility of adaptive catalytic systems deals with development of sustainable technologies and industrial processes based on natural resources. Independent development of nanotechnology, materials science and catalysis has led to the discovery of common fundamental principles of the surface chemistry of chalcogen compounds. The advantages of selenium: This Review focuses on the structure and properties of selenium-based self-assembled monolayers (SAMs). Comparison between well-known sulfur-based SAMs and newly developed selenium monolayers revealed outstanding complimentary features in their surface chemistry and the key role of headgroup element is highlighted. The application of selenium-containing metallic species in catalysis is also discussed.