A 20 ns molecular dynamics simulation was performed with a realistic model system of sodium octanoate micelles in aqueous solution. The system comprised three micellar aggregates, each containing 15 monomers, and 15 free octanoate monomers. The initial configuration relaxed within 2 ns, mostly due to the fusion of aggregates and the exchange of monomers between the aggregates and the solution. The process led to a decrease in the total number of octanoate clusters and to an increase in the average aggregation number and micellar radius, observations in agreement with experimental results. (c) 2005 Elsevier B.V. All rights reserved.