We investigated natural convection heat transfer around a radial heat sink adapted for dissipating heat on a circular LED (light emitting diode) light and optimized heat sink. The numerical results were validated with experimental results and it showed a good agreement. To select the optimum reference model, three types of heat sinks (L, LM and LMS model) were compared. Parametric studies were performed to compare the effects of the number of fins, long fin length, middle fin length and heat flux on the thermal resistance and average heat transfer coefficient. Finally, multi-objective optimizations considering thermal performance and mass simultaneously were performed and Pareto front were conducted with various weighting factors. It was found that it was impossible to optimize both thermal performance and heat sink mass at the same time, and there existed an upper limit to the ratio of weighting factors (omega(1)/omega(2)). (c) 2011 Elsevier Ltd. All rights reserved.