In this paper, natural convection heat transfer of parallel-plate rectangular fins heat sink positioned at a certain angle on the vertical substrate was experimentally investigated. Experiments were done with an aim to examine and evaluate the enhancement of heat transfer by deploying fine water mist into ambient air under a range of input power. To empower this investigation, a special purpose experimental set-up was constructed and developed so as to perform experiments on both air and water mist cooling scheme. The water mist concentration influences on the heat transfer enhancement was examined for (mw=90 – 430 mL/h), while the surface temperature varies from 29 to 110 °C. Experimental results revealed that the heat transfer enhancement increase and reached its maximum value under mw=430 mL/h. The average heat transfer enhancement increases by about 1.28%, 1.81%, 2.37%, and 2.83% when compared against traditional air cooling under (mw=90 – 430 mL/h). In addition, influence of water mist on the fin spacing, fins number, and dissipation area was also examined.