Surface roughness is one of the important quality characteristic of a micromachined component. This paper presents a model to predict surface roughness of micro-EDmachined surfaces. The model is based on the configuration of a single-spark cavity formed as a function of process parameters. Assuming the normal distribution of surface heights, the and of the surface profile are evaluated after every spark. The model was further extended to capture the role of debris in micro-EDM in changing electric potential at the micropeaks on the cathode surfaces. The chemical kinetics approach was used to evaluate the change in plasma enthalpy and composition as a result of debris inclusion in the dielectric. The corresponding energy distribution between the electrodes was used to predict configuration of the single-spark cavity and the consequent surface roughness using the earlier surface roughness model. The modeling results were found to agree well with the micro-EDM validation experiments performed without and with the inclusion of artificial debris (iron particles) in the dielectric.