Adsorption reaction constants of chicken egg lysozyme of 0-1000nM prepared with potassium phosphate buffer solution (PPBS) of 7.0 mM and at pH = 11.0 on the surfaces of nanosilica and nanodiamond of diameter 100nm by fluorescence method have been determined as 4.0 x 10(7) and 1.5 x 10(8) nM(-1), respectively. The Langmuir isotherm can be well followed under the assumption of monolayer adsorption on both surfaces. The available surface areas per individual lysozyme molecule adsorbed on nanosilica and nanodiamond within the linear regions of Langmuir isotherms can be approximated with 2 and 10nm(2), respectively.