High heat flux at low excess temperature is the prime factor in pool boiling heat transfer. One of the methods to enhance peak heat flux in nucleate boiling is sur-face modification. The substrate of the copper has been modified by SiO2 thin film coating. The coating was performed on the substrate at three different thicknesses 250 nm, 500 nm, and 750 nm. The thin film coating was done by sputtering technique. The water contact angle was measured for bare and SiO2 thin film coated substrates. The contact angle decreased drastically because of more nucleation sites involved for wetting the substrate. The coating characteristics re-ported that the wettability of the copper substrate plays an important role in the critical heat flux enhancement. The critical heat flux test was carried out for bare copper substrate and SiO2 thin film coated copper substrates. The SiO2 thin film coating exhibited superhydrophillic nature on the substrate because of greater wettability. The superhydrophillic nature of the substrate enhanced the peak heat flux significantly. Also the boiling heat transfer coefficient was improved at high heat flux in nucleate boiling regime.