Abstract Oat β-glucan was partially degraded with (1→4)-β- d-glucan 4-glucanohydrolase for different periods of time. Weight average molecular weight and weight average intrinsic viscosity were obtained from SEC-RI-RALLS-Visc and ranged from 2200 to 213,900 g/mol and 7 to 316 ml/g, respectively. The viscosity equation determined [ η ̄ ] w =1.06×10 −2 M ̄ w 0.86 indicated an extended random coil conformation. When the coil was modelled as a worm-like chain a persistent length of 3.65 nm was obtained. The hydrolysis products identified after extensive degradation were glucose, cellobiose, laminaribiose, 4- O-β-laminaribiosyl d-glucose, 4- O-β-laminaribiosyl d-cellobiose and 3- O-β-cellobiosyl d-cellobiose showing that other enzyme activities were present. The depolymerization kinetics suggested that longer sequences of consecutive (1→4)-linkages represent fast hydrolysable sites and the presence of higher relative proportions of (1→3)-linkages restricts the affinity of the enzyme.