Gas turbine hot section components are being pushed to the limit with every increasing combustion firing temperatures and improved expectations of life and durability. Gas path components inside gas turbines see some of the harshest conditions including high pressure and temperatures. It is imperative that heat transfer plays a major role in the evaluation and survival of these components. An overview of the challenges in gas turbine heat transfer measurements and design of cooling systems will be discussed in this presentation. Two major issues will be focused on during the talk. The study of heat load in gas turbine combustors will be presented using a realistic combustor experiment. The measurements inside the optical combustor will be made using PIV and Infrared thermography. Detailed flow and heat load measurements will help in understanding the complex interactions in the reacting flow and help design cooling for modern low emission combustors. The other study will focus on advanced cooling designs for turbine airfoils. Improved internal cooling of turbine blades is a critical need for the interest. With the advent of additive manufacturing, the designs of internal cooling feature options are unlimited. With that in mind, detailed heat transfer measurements are presented for complex internal cooling channels with and without rotation to evaluate performance and applicability of such cooling designs to turbine blade cooling. Aspect of additively manufactured complex designs as a tool to enhance heat transfer compared to conventional manufacturing methods are discussed. The cooling channels have features such as ribs, dimples, impinging jets and a combination of these features. The challenge of making detailed measurements inside such rotating channels is displayed through the measurements. In addition, some examples of additively designed geometries are demonstrated.