Viscosity of cereal β-glucan during digestion is considered to be a vital factor for its health effects. Thus, studies on solution properties and gelation are essential for understanding the mechanisms of the β-glucan functionality. The aim of this study was to investigate the effect of the dissolution temperature on gelation of cereal β-glucan at low concentrations that are relevant for food products. The rheological properties of oat and barley β-glucans (OBG and BBG) using three dissolution temperatures (37 ˚C, 57 ˚C and 85 ˚C) at low concentration (1.5% and 1%, respectively) were studied for 7 days. Additionally, the β-glucans were oxidised with 70 mM H2O2 and 1 mM FeSO4×7H2O as a catalyst, to evaluate the consequence of oxidative degradation on the gelation properties. The study showed that dissolution at 85 ˚C did not result in gelation. The optimal dissolution temperature for gelation of OBG was 37 ˚C and for gelation of BBG 57 ˚C. At these temperatures, also the oxidised OBG and BBG gelled, although the gel strength was somewhat lower than in the non-oxidised ones. Gelation was suggested to require partial dissolution of βglucan, which depended on the molar mass and aggregation state of the β-glucan molecule. Therefore, the state of β-glucan in solution and its thermal treatment history may affect its technological and physiological functionality.