Thermal-assisted processes are used for various applications, namely metal machining, heat treatment, deposition of materials (coating), destroying the biological cells—cancer cells (medical) in general, and nanoparticle generation. A thermal-assisted process uses a thermal energy in the form of beam or plasma. This entry focuses on nanoparticle generation using mechanical micromachining technique micro-electrical discharge machining (µ-EDM), which is one of the thermal nontraditional machining processes. The features (microholes and microchannels) are obtained by removing tiny bit of materials using a repetitive spark discharge that appears between the cathode (tool) and the anode (workpiece). However, no one has paid attention on the debris removed from the electrode materials. This entry focuses on these debris and their characterization. By closely controlling µ-EDM processes’ parameters, namely voltage, current, duty cycle, and pulse duration, it is possible to generate a large quantity of nanoparticles of required size and morphology. A complete investigation has been carried out to generate the copper and aluminum nanoparticles using tailor-made µ-EDM system and characterize using various diagnostic studies, namely transmission electron microscopy and scanning electron microscopy. To study the suitability of generated nanoparticles, concentration, thermal conductivity, and viscosity studies have also been carried out. The characterized nanoparticles are found to be less than 10 nm with high yield. Thermal conductivity and viscosity of colloidal nanoparticles were found to be enhanced as compared to the base fluid.