Nano materials have made a revelation in all fields of engineering and technology. Materials of size less than 100 nm are termed as nano materials. The excellent properties of nano materials have attracted the scientists and engineers more towards nano technology. Solid nano particles dispersed in the base fluids such as water or ethylene glycol are called nanofluids, especially used to increase the heat transfer capability of base fluids. In this work we have synthesized Al2O3-Cu nano composite powder in a thermo chemical route that involves the preparation of precursor powder from metal nitrates and hydrogen reduction technique. Two different proportions of precursors were used to obtain the nano composites of two different proportions. The prepared powder was characterised using XRD, SEM and EDS. Water based hybrid nanofluids were prepared and their stability have been studied for different volume concentrations.