This work illustrates the complexity of protein adsorption by ion exchange and hydrophobic interactions and the important role of nonspecific effects in the establishment of the adsorptive process. In ion exchange the interaction mechanism between chymotrypsinogen and lysozyme and two commercially available cation-exchange resins at different pH values and salt concentrations was studied. In hydrophobic interaction, the effect of temperature on the adsorption mechanism of bovine serum albumin onto epoxy-(CH2)4-sepharose was analyzed. In both cases observations have been made with respect to the results obtained from flow microcalorimetry. A direct correlation between the heat of adsorption data and isotherm measurements were observed.