Flow microcalorimetry was used to study the adsoption of anionic alkyl surfactants from aque--ous solutions onto silica. It is found that for alkyl sulfate systems the strength of adsorption interactionincreases with increases of the alkyl chain length and decreases as temperature rises. The adsorptiondepends only on monomer concentration of the solution even above the critical micelle concentration(cmc). The assumption is made that the adsorption involves only a transfer of monomers from bulkto surface phase. A different adsorption mechanism is operative for the alkyl carboxylate. Flow microcalorimetry was used to study the adsoption of anionic alkyl surfactants from silica. It is found that for alkyl sulfate systems the strength of adsorption interaction in creases with increases of the alkyl chain length and decreases as temperature rises. on monomer concentration of the solution even above the critical micelle concentration (cmc). The assumption is made that the adsorption involves only a transfer of monomers from bulk to surface phase. A different adsorption mechanism is operative for the alkyl carboxylate.