Abstract: This review provides a comprehensive and systematic overview of recent advances in the synthesis, functionalization, and separation-related applications of hydrogen-bonded organic frameworks (HOFs) and their composite materials. HOFs represent an emerging and distinctive class of crystalline porous materials, constructed from organic building blocks via directional hydrogen bonding and other non-covalent interactions. They exhibit several advantageous characteristics, including high crystallinity, structural tunability, mild synthesis conditions, facile regeneration and solution processability. These inherent properties, particularly their designable pore environments and functionalizable surfaces, render HOFs highly promising for advanced separation processes that demand precise molecular recognition and efficient mass transfer. The first part of the review summarizes the principal design strategies, synthetic methodologies and post-synthetic modification techniques for HOFs. Key preparation methods such as solvent evaporation, solvothermal synthesis, and self-assembly are detailed, alongside advanced fabrication approaches like in-situ growth on substrates. The underlying assembly mechanisms, critical operational parameters, and the applicability scope of each technique are critically examined. A dedicated discussion on post-synthetic modification strategies, including chemical grafting and functional group transformation, highlights pathways to tailor HOF properties without compromising framework integrity. Emphasis is placed on how these synthetic and modification choices directly influence the resulting material's structural robustness, porosity characteristics, and ultimate functional performance. The second part delves into the diverse applications of HOF-based materials across separation science. In chromatographic separation, the utilization of HOFs as novel stationary phases for gas chromatography and capillary electrochromatography is discussed. Their exceptional selectivity originates from well-defined pore structures, uniform pore apertures, and tailored surface functionalities that differentially interact with analytes. In the domain of sample pretreatment and enrichment, the applications of HOFs and their composites in various extraction techniques including dispersive solid-phase extraction, solid-phase microextraction and magnetic solid-phase extraction, are systematically reviewed. Their demonstrated high extraction efficiencies, rapid adsorption kinetics and excellent reusability are highlighted. Furthermore, the review thoroughly examines the adsorption and removal capabilities of HOFs toward a wide spectrum of environmental pollutants. This encompasses the capture of heavy metal ions, sequestration of radionuclides, recovery of volatile iodine, and removal of organic dyes from aqueous solutions, showcasing their high adsorption capacities, superior selectivity, and stability under challenging conditions. Throughout the discussion, the inherent advantages of HOFs, such as their predesignable frameworks, high specific surface areas, modular functionality and unique self-healing properties, are continuously linked to their separation performance metrics. Key structure-property relationships that govern the selectivity, adsorption capacity, kinetics, and recyclability of HOF-based separation media are elucidated. This analysis provides fundamental insights to guide the rational design of next-generation HOF materials for targeted and challenging separation tasks. In conclusion, this review consolidates both theoretical insights and practical methodological guidance to support ongoing fundamental research and to accelerate the practical implementation of HOFs in separation science. Future perspectives on emerging trends and a discussion of remaining challenges, particularly concerning long-term stability under real-world conditions, scalable and cost-effective manufacturing, and overall commercial viability, are presented to stimulate continued innovation in this dynamic and rapidly evolving field.

Key words: hydrogen-bonded organic frameworks, composite materials, preparation strategies, chromatographic separation, extraction and enrichment, adsorption removal