This study describes the comprehensive characterization of the diverse water-based nanofluids involving aluminum oxide, titanium dioxide, and zinc oxide nanoparticles, which were prepared through the two-step synthesis method assisted by a microemulsion ultrasound skill with effects of both weight-percent concentration (wt.%) in the range of 1.0% and 5.0% and between 20 °C and 40 °C. The mean cluster size, zeta potential, pH value, viscosity, thermal conductivity, absorbance, light absorption, and electrical charge density of the various nanofluids were surveyed by relative experiments. The results showed that the 2 wt.% Al₂O₃, 2 wt.% TiO₂, and 1 wt.% ZnO nanofluids were preferentially prepared with a good suspension stability through four weeks. The thermal conductivity and the power generation increased with an increase in temperature. The present synthesis method is suitable for fabricating the metal oxide nanofluids at a temperature between 20 °C and 40 °C and a concentration of 1 wt.% to 5 wt.%.