The aim of the present paper is to study the two-dimensional steady natural convection heat transfer to water based nanofluids flowing over cylinder. The governing equations are reduced to a system of ordinary differential equations by using the group method and similarity transformations. These equations are then solved numerically by using fourth- order Runge-Kutta algorithm supported by the shooting technique. In the numerical results, the velocity components, shear stress, pressure, temperature and heat flux inside the boundary layer are obtained for various values of nanoparticle volume fraction ϕ and different types of nanofluids (silver-water, copper-water, titanium-water and alumina-water). The results shows that the velocity components, temperature and pressure distribution in the boundary layer decrease as increases of nanoparticle volume fraction. To check the behavior and performance of the flow and heat transfer, a comparison of different types of nanofluids is illustrated. It is found that the silver nanoparticles achieve the highest value of temperature due to high thermal conductivity and also they achieve the highest value of pressure due to high density compared to the other nanoparticles. Moreover, the radial velocity and the axial velocity are the highest for alumina-water nanofluid compared to the titanium-water, copper-water and silver water.