The present investigation deals with experimental study related to natural convection boiling of acetone-isopropanol-water ternary mixtures on a horizontal plain tube al atmospheric pressure. The heat transfer coefficients of ternary mixtures depend on the concentrations of the light components and heat flux. The wall superheat required for the boiling of any composition of ternary mixture is greater than that either of pure components. The correlation proposed by Theme and Shakir for multicomponent mixtures has been found to correlate data within absolute mean error of +/- 5.16%.