Nanofluids can improve heat transfer characteristics compared to base fluids. The increase in heat transfer is influenced by the thermal properties of the nanofluid. The nanofluid used is a mixture of ethylene glycol/water added with TiO2 nanoparticles. Nanofluid at a temperature of 27 °C was applied to a shell and tube heat exchanger to determine the characteristics of heat transfer. In the process of synthesis of nanofluids prepared, such as (1) water; (2) ethylene glycol; (3) ethylene glycol-water with volume ratios of 40:60, 60:40, and 80:20; (4) PVP surfactant; and (5) TiO2 nanoparticles with a concentration of 0.05. The method used in the synthesis of nanofluids is a two-step method. The effect of ethylene glycol-water mixture ratio and water flow on the heat exchanger studied in this study. The nanofluid (cold fluid) used in the heat exchanger is 0.3. 0.6 and 0.9 L/min, while the water flow rate (hot fluid) used was 0.7 L/min at 60 °C. The results of this study indicate that the highest heat transfer efficiency value is nanofluid with ethylene glycol-water 40:60 at a water flow of 0.9 L/min. © 2023 American Institute of Physics Inc.. All rights reserved.