This thesis investigates the impact of additive manufacturing induced surface roughness on the heat transfer mechanisms within gas turbine cooling channels. The study involves the design and utilization of a Particle Image Velocimetry (PIV) experimental rig. The research focuses on understanding how the AM roughness affects the flow behavior and heat transfer in micro-channels. Results demonstrate that flow stagnation points significantly contribute to the heat transfer enhancement. High turbulence regions, especially following large roughness elements show an increased heat transfer. Secondary flow features were identified close to the wall, like high-speed streaks. However, the findings show the necessity to further develop the PIV system for closer wall measurements to capture localized effects due to the roughness.