In the present research, an experimental investigation was conducted to identify the behaviour of gallium as a promising heat transfer fluid for cooling a high heat flux surface. Bismuth nanoparticles were dispersed within the gallium to compensate its poor thermal conductivity and to enhance its wettability. A high-fidelity experimental setup was fabricated to provide conditions for measuring the contact angle between the gallium and the surface and also to measure the heat transfer coefficient of a free surface liquid film flowing on the heating surface. Influence of different operating parameters including tilt angle of the surface, heat flux of the surface, surface roughness and time on the contact angle and heat transfer coefficient of the liquid film was experimentally investigated. Results showed that with an increase in the tilt angle of the surface, higher heat transfer coefficient can be achieved, which was attributed to the enhancement of the terminal velocity of the liquid metal. Also, an increase in the roughness of the surface intensified the contact angle of the liquid metal and caused a decrease in the wettability. It was also found that the contact angle of gallium was a function of time such that it decreased with time spanning and reached a constant value.