Abstract This study explores the relationship between the recast layer zone and the electrical discharge machining (EDM) process parameters behaviors on metal matrix composites (MMCs). The characteristics of recast layer are investigated by using a L27 Taguchi’s design of experiments. The formation of recast layer in three types of aluminum based particulate reinforced MMCs have been examined in combination with process parameters in the variant dielectric medium. The influence of each selected parameter is obtained by ANOVA analysis. It is found that the formation of recast layer is significantly affected by the reinforcement architectures in matrix phase and the spark energy of EDM. The cross-sectional micrograph of recast layer is assessed for the metal removal mechanism and EDM-induced surface alterations on the machined zone.