A cooling system and method that significantly improves spray evaporative cooling by using a mixture of cooling fluids having different boiling points. The cooling fluid mixture is sprayed onto a surface to be cooled. Efficient cooling with reduced cooling fluid volume is provided by both evaporation of the more volatile component of the mixture as well as heating of the less volatile component which remains in contact with the surface being cooled. More uniform temperatures across the surface being cooled and a reduced risk of potentially damaging critical heat flux is achieved.