The green synthesizing of hybrid nanofluids is a promising method for producing advanced nanoscale materials that can improve the efficiency of various thermal systems while minimizing their environmental impact. This approach is consistent with the broader goals of sustainable and environmental nanotechnology. The present study investigates the optimization of the mixing ratio of clove-treated MWCNTs (CT-MWCNTs)/TiO2 nanomaterials. To find the optimal nanoparticle mixing ratio, five water-based hybrid samples were prepared and tested with different mixing ratios: 20:80, 40:60, 50:50, 60:40, and 80:20 (CT-MWCNTs:TiO2) at a fixed concentration of 0.1 wt. The thermal conductivity and dynamic viscosity measurements were recorded at a temperature range of 30�50 °C. Results revealed that the ideal mixing ratio with the highest thermal conductivity and lowest possible viscosity was found to be 60:40 based on the thermophysical performance factor (TPF). It is also concluded that hybrid nanofluids possessed higher performance as compared with mono nanofluids. © 2023