Among various material removal processes, Wire-EDM is considered as an effective process for the machining of modern composite materials. Its inherent capability for automation is another feature which fulfils the expectations of modern manufacturing industries. Wire-EDM is a complex machining process controlled by a large number of process parameters. In the present study an attempt has been made to find the effect of process parameters such as peak current, pulse on time, pulse off time, workpiece thickness and wire feed rate over different machining performance characteristics such as cutting rate, surface roughness and wire wear ratio. Taguchi based L27 orthogonal array has been used for conducting experiments. Analysis of variance (ANOVA) technique was used to find out the variables affecting the performance characteristics. A mathematical model has been developed for each machining performance using reweighted least square method to create relationships between process factors and responses. Results from the analysis show that the workpiece thickness, pulse on time and peak current are the most effective parameters affecting the cutting rate, surface roughness and wire wear ratio respectively.