Due to their unique properties, the synthesis of nanoparticles and other nanomaterials, such as nanocomposite hydrogels, attracts great interest, both in science and engineering. In recent years, the emphasis has been on alternative, environmentally friendly methods of synthesis. Gamma-irradiation synthesis is a relatively new and efficient method for synthesis of nanoparticles and hydrogels. Its main advantages over classical synthesis methods are homogeneous, clean and temperature-independent initiation of reactions, and a sterile final product. In this work, the possibility of one-step synthesis of poly(ethylene oxide) (PEO)/Ag nanocomposite hydrogels by gamma-irradiation was studied. For this purpose, the influence of different experimental parameters was investigated. PEO/Ag hydrogels and colloidal suspensions were synthesized by gamma irradiation of PEO and Ag+ aqueous solutions, depending on the molecular weight and weight precentage of the polymer, initial Ag+ concentration, absorbed dose, pH value and atmosphere in which irradiation was carried out. Synthesis at elevated pH, more concentrated PEO solution and under inert atmosphere enabled formation of hydrogels with a higher concentration of silver nanoparticles. UV-Vis spectroscopic measurements showed characteristic absorption maxima at approximately 400 nm, indicating the formation of silver nanoparticles. SEM microscopy confirmed the formation of silver nanoparticles, which were small in size (~11 – 23 nm) and homogeneously distributed within the polymer matrix. Smaller particles were formed at lower silver concentration, at higher pH values and upon irradiation in an inert nitrogen atmosphere. XRD analysis also confirmed the formation of silver nanoparticles, and together with the results of DSC analysis provided information on the crystallinity and hence crosslinking density of the obtained gels. The degrees of crystallinity showed the lowest values at higher dose, on irradiation in inert atmosphere and lower concentration of PEO and Ag+, which indicates a greater degree of crosslinking of PEO chains. Irradiation with a higher dose resulted in almost amorphous gels with significantly reduced melting and crystallization temperatures.