Experimental techniques are important for obtaining measurements on heat-transfer surfaces. Cooling designs depend on experimental correlations that cover the entire range of parameters that affect that particular design. Design correlations have been developed by researchers who conducted experiments for actual components or for simplistic models. Researchers opt to use experimental methods that are most applicable for the test model and the kind of results they expect to obtain. Depending on the experimental measurement tool and the available capability, experiments can be run at low temperature or high temperature. Also, some experiments can only provide either heat-transfer coefcient measurements or lm effectiveness measurements, whereas some techniques can provide both for lm-cooling situations. Also, researchers have used mass-transfer measurements to obtain heat-transfer results with heat-/mass-transfer analogy. Optical, surface visualization techniques are also popular. In addition to surface heattransfer measurements, it is also important to characterize the ow behavior. There are several ow eld and thermal eld measurement techniques. We have attempted to discuss each experimental methodology in this chapter so that the reader can understand how the data presented in the earlier chapters were acquired.