Technical Abstract: Extruded breakfast cereals (EBC), processed from two oat lines, N979-5-2-4 (N979) and ‘Jim’, with beta-glucan concentrations of 8.7 and 4.9%, respectively, were used to determine the impact of dry solids (DS) and bile acid (BA) concentrations on in vitro BA binding efficiency. A full fractional factorial design with levels for BA concentration of 0.20, 0.47, 0.95, 2.37, and 4.73 'mol/g of total EBC slurry, and for DS in the slurries of 0.8, 2, 3 and 4% (w/w) was selected. The absolute amount of BA bound ('mol), percentage (%) BA bound based on the total amount of BA added, and BA bound per gram of DS the EBC ('mol/g) were measured and calculated. N979 in vitro digestion slurries had greater BA binding ('mol), than Jim slurries at different DS and BA concentrations, with greater differences at DS of 3% or above and at BA concentrations of 2.37 'mol/g or above. No difference in absolute amount of BA bound ('mol) and percentage (%) BA bound occurred between the EBC slurries made from the two oat types at the lowest DS of 0.8% or lowest BA concentration of 0.20 'mol/g. The efficiency of BA binding by beta-glucan in these two EBC became comparable at 3% DS or above and BA concentrations of 2.37 µmol/g or above, indicating these two conditions can be employed to measure BA capacities for similar foods. Also, the beta-glucan in the EBC produced from the N979 oat line was more soluble than that from the EBC produced from the Jim oat line. Thus, greater BA binding capacity may have been caused by both greater amount of beta-glucan and greater solubility of beta-glucan in N979 than in Jim EBC.