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Turbulent flow convective heat transfer and friction factor characteristics of Al2O3/water nanofluid flowing inside a uniformly heated horizontal circular tube are conducted in this Letter. To do this, Al2O3 nanoparticles of 40 nm size were characterised and dispersed in distilled water to form stable suspension containing 0.1, 0.5, 1.0, 1.5 and 2.0 volume concentrations of nanofluids. Results indicate that heat transfer coefficients increase with nanofluid volume concentration and do not change with Reynolds number. The enhancement of the Nusselt number is about 22 at Re 13 500 using 2 alumina nanoparticles compared to distilled water. Experimental results are also compared with the existing correlations of convective heat transfer coefficient and pressure drop in turbulent regime. The measured pressure loss when using nanofluids is almost equal to that of the base fluid.