The mechanical properties of the particulate reinforced composites are profoundly affected by two significant factors, fraction of reinforcement in the matrix and the distribution of the reinforced particles in the matrix. In this paper, a novel approach is adopted where a newly developed distribution index and area fraction of the composites are quantitatively determined through microstructural image analysis method, and the process parameters are optimised for maximum area fraction and minimum distribution index. The distribution index ( D index ) is calculated by estimating the free-path spacing within particles. The stir casting process parameters (stirrer rpm, time of stirring, furnace temperature and preheat temperatures) are optimised by Box-Behnken design of response surface methodology. The quantitatively assessed responses provide an authentic base for optimisation of process parameters. The experimental responses corresponding to the optimised parameters are within the range of the responses estimated by the confirmation test of optimisation with a 95 % confidence level.