Nanotechnology plays an important role for the development of the modern technology. In nanotechnology heating or cooling of the nano-devices are very important for their proper functionality. Nanofluids have novel properties that make them potentially useful in many applications of heat transfer. They exhibit enhanced thermal conductivity and the convective heat transfer coefficient compared to the base fluid. Thus, nanofluids are treated as engineered colloids 21st century modern fluids. In this thesis I use numerical technique to investigate the heat transfer characteristics of a two-dimensional steady hydromagnetic convective flow of nanofluids composed of three types of nanoparticles (copper, aluminium oxide and titanium oxide) and three kinds of base fluids (water, ethylene glycol and engine oil). The nanofluids flow over a nonlinear inclined stretching surface in which the effect of convective surface condition in taken into consideration. Using similarity transformations, the governing nonlinear partial differential equations of the physical model are transformed into nondimensional ordinary differential equations and solved for local similar solutions using very robust computer algebra software, Maple 13. The numerical simulation is carried out to investigate the role of the pertinent parameters in the flow of the nanofluids, temperature fields, rate of heat transfer and rate of shear stress. It is found that the nanofluids velocity and temperature distributions are significantly influenced by the physical parameters entering into the analysis. The results show that the type of nanofluid is a key factor for heat transfer enhancement. I also found that addition of nanoparticles to the base fluid may not always increase the rate of heat transfer. It significantly depends on the type of base fluid and surface convection parameter. This finding is new and has not been reported in any open literature.