In this study, tube side thermal and hydraulic performance of a mini channel shell and tube heat exchanger (MC-STHE) designed using Kern method was investigated experimentally for water and α-Al2O3/water nanofluids prepared in two different low volume fractions (0.02% and 0.2%). The average particle diameter of Al2O3 nanomaterial used in the preparation of nanofluids is 50 nm. The copper tubes (L/D=120) with inner diameter of 2 mm and outer diameter of 3 mm and a length of 240 mm were used in the MC-STHE. During the experiments, shell side water flow rate was kept constant at 180 L/h, while the water and nanofluids flow rates on the tube side were changed between 60-600 L/h. The use of nanofluids in the MC-STHE deteriorates tube side convective heat transfer coefficient in the flow rates below 125 L/h, while enhancing convective heat transfer coefficient in the flow rates above 125 L/h, compared to water. The enhancement ratios for convective heat transfer coefficient compared to water were found to be 0.82-1.66 for 0.02% Al2O3/water and 0.9- 1.74 for 0.2% Al2O3/water in the range of 60-600 L/h volume flow rates. However, in the applications in which enhancement of the heat transfer is desired, it was obtained that the increase in pumping power should be taken into consideration depending on the selected nanofluids volume fraction. According to efficiency index in which increase in heat transfer and pressure drop compared to water are evaluated together, it was found that the use of nanofluids was significant in the flow rates above 375 L/h for 0.02% Al2O3/water and in the flow rates above 300 L/h for 0.2% Al2O3/water. The use of mini-channel increased the compactness by decreasing the weight and volume of the heat exchanger, and in addition to this, higher heat transfer coefficients were obtained by using nanofluids instead of water.