In the present work, theoretical performance comparison of stepped solar still using different nanofluids is performed. Four nano fluids are used in this study. The used nano- particles are aluminium oxide, Copper oxide, Titanmum dioxide, and Silicon oxide. The effect of nano-particles volume fraction on the still daily productivity and efficiency are studied. The estimated cost to produce  one distalled liter for conventional and stepped solar stills with and without nano-particles is obtained. It is found that using a nano-fluid may slightly increase the still productivity. Finally a good agreement between the present theoretical work and previous experimental results has been obtained.