The effect of protein concentration on bovine serum albumin (BSA) aggregation kinetics at high concentration was studied by differential scanning calorimetry (DSC). The nonisothermal kinetic analysis of this process was carried out using a composite procedure involving the isoconversional method and the master plots method. The observed aggregation process was characterized by denaturation temperature (T-dmax), apparent activation energy (E), the apparent order of reaction (n), and pre-exponential factor (A) which all increased with the increase of BSA concentration. The results suggested that the apparent aggregation reaction of BSA approximately conformed to the simple order reaction model. The higher BSA concentration, the higher the apparent order of reaction and the more close to 2 was. The difference intrinsic fluorescence of BSA between before and after the thermal denaturation and aggregation provided the evidences of conformation changes of BSA and the substantial impact of BSA concentration on aggregation. This study showed the combination of iso-conversional method and the master plots method could be used to model the aggregation mechanism of the protein. (C) 2007 Elsevier B.V. All rights reserved.