A quantitatively correct kinetic model for the temperature-induced denaturation and aggregation of β-lactoglobulin is presented. The model recognizes an initiation, a propagation and a termination step by analogy with polymer radical chemistry. The decrease in native β-lactoglobulin is predicted to follow order 3/2, in agreement with experimental results. The size of the protein polymer particles is predicted to be proportional to the square root of the initial β-lactoglobulin concentration. The scattered light intensity is proportional to the product of concentration and size of the protein polymer particles. The initial increase in scattering intensity of the particles therefore scales with the initial squared β-lactoglobulin concentration. The influence of other reaction conditions, e.g. ionic strength and pH, can be incorporated via the reaction constants of the reaction kinetic pathway.