We report effective passivation of silicon surfaces by heating single crystalline silicon substrates in liquid water at 110°C for 1 h. High values of photo-induced effective minority carrier lifetime τeff in the range from 1.9x10-4 to 1.8x10-3 s were obtained for the n-type samples with resistivity in the range from 1.7 to 18.1 Ωcm. τeff ranged from 8.3x10-4 to 3.1x10-3 s and from 1.2x10-4 to 6.0x10-4 s over the area of 4 inch sized 17.0 Ωcm n- and 15.0 Ωcm p-type samples, respectively. The heat treatment in liquid water at 110°C for 1 h resulted in low surface recombination velocities ranging from 7 to 34 cm/s and from 49 to 250 cm/s for those 4 inch sized n- and p-type samples, respectively. The thickness of the passivation layer was estimated to be approximate only 0.7 nm. Metal-insulator-semiconductor type solar cell was demonstrated with Al and Au metal formation on the passivated surface. Rectified current voltage and solar cell characteristics were observed. Open circuit voltage of 0.47 V was obtained under AM 1.5 light illumination at 100 mW/cm2.