Spray cooling is known as an effective and efficient method of removing heat from hot surfaces. One of its many applications is the cooling of electronic components. In order to keep the hot components within the limits of their maximum allowable temperature, the process conditions are typically selected such that the impinging droplets partially evaporate at the hot wall. In the seminar lecture, the basic heat transport phenomena essential to this process will be described and characterized in detail. For this purpose, both spatially and temporally high-resolution experimental investigations and corresponding numerical simulations were carried out. Both single droplets and interactions of coalescing droplets wer e investigated. Due to the dynamics during droplet impact, the hot wall is first wetted by the liquid and then partially dewetted again. The results show that other heat transport processes dominate in these different phases of wetting and dewetting. The relevant length scales are very different too. They extend either only over the region immediately at the moving 3-phase contact line or over the thermal boundary layer or over the entire mass of the liquid phase. These phenomenological differences are explained and quantified by means of exemplary investigations.