The heat-induced desorption and adsorption of the proteins lysozyme, ribonuclease A, bovine serum albumin, and fibronectin at protein layers was investigated in two different environments: pure buffer and protein solution. Using two different environments allows us to distinguish between thermodynamic and kinetic mechanisms in the adsorption process. We observed a desorption in buffer and an adsorption in protein solution, depending upon protein properties, such as size, stability, and charge. We conclude that the desorption in buffer is mainly influenced by the mobility of the proteins at the interface, while the adsorption in protein solution is driven by conformational changes and, thereby, a gain in entropy. These results are relevant for controlling biofilm formation at solid-liquid interfaces.