The development of pH-sensitive delivery systems was addressed by [PERSON] and collaborators from Peking University, who showed that the \(\gamma\)-radiation-initiated polymerization of cyclic ethers in aqueous solution led to the pH-controlled formation of microspheres or micelles [10]. Such microcapsules may be used in drug delivery systems or in the oil extraction industry. One of the key applications of radiation technology is the processing of polymeric materials and composites in order to render them new, unique features. [PERSON] et al. from Universite de Reims Champagne Ardenne proved that the radiation-induced curing of epoxy-aromatic resins is less sophisticated and less time consuming than the conventional thermal curing and produces high-performance composites of an enhanced durability [11]. The application of ionizing radiation to the processing of nature-derived materials was the subject of four papers [12; 13; 14; 15]. [PERSON] and co-workers from the Hubei University of Science and Technology and Huazhong Universities of Science and Technology developed a method of bamboo sawdust modification through the radiation-induced grafting of glycolidyl methacrylate and further ring-opening reactions with amine-containing compounds. They evidenced that phosphates absorption by the product may be enhanced by amines modifications [12]. Compared to conventional synthesis, the radiation method reduced the synthesis time from tens of hours to several minutes. The paper by [PERSON]'s group from the University of Maryland raised the problem of food packaging subject to radiation disinfection [13]. The authors showed that the radiation-induced modification of biodegradable poly(lactic acid) film used for food packaging did not change the gas permeability property, and the degradation of polymer chains could accelerate the decomposition of composted packaging. The processing of natural polymers with ionizing radiation was also explored by [PERSON] and [PERSON] from the National Institutes for Quantum and Radiological Science and Technology. They used a radiation crosslinking technique to synthesize biodegradable cellulose derivative-based hydrogels for soft contact lenses [14]. Multicomponent hydrogels have an excellent transparency and possess mechanical properties adequate to the proposed application. The paper by [PERSON] and collaborators from the Lodz University of Technology and the Universita degli Studi di Palermo described the results of the radiation-induced crosslinking of polysaccharides modified with hydroxypropyl and carboxymethyl functional groups to produce dual stimuli-responsive hydrogels [15]. The authors demonstrated that the extent of water uptake can be easily tuned by the composition and the radiation dose, and further controlled by the pH and temperature of the aqueous environment. This Special Issue provides an insight into the recent developments and current trends in applications of radiation chemistry in various fields, including medicine and pharmacology, environment protection, material engineering and the nuclear power industry. The versatility of materials synthesized or modified without the use of harmful additives allows radiation technologies to be environmentally friendly and contributes to sustainable development. Conceptualization, writing and editing D.S.-W., Y.K. and R.A.W. All authors have read and agreed to the published version of the manuscript. This research received no external funding. We express thanks and congratulations to all the professional authors of the accepted manuscripts. We appreciate and are very grateful to all the reviewers of the submitted manuscripts for their feedback, comments, and suggestions in helping the authors to improve their papers. Finally, this Issue would not be possible without the dedicated editorial team of _Applied Sciences_. The authors declare no conflict of interest.