Abstract: The present invention relates to a method and a device for determining temperature-dependent parameters, such as the association/dissociation parameters and/or the equilibrium constant of complexes that comprise at least two components, wherein the first components, which are in a liquid phase, are contacted with measuring points located preferably on a planar optical waveguide of a reaction carrier and formed by second components linked to the solid reaction carrier and specifically binding to said first components, with the aid of a preferably heatable means for contacting the liquid phase and the reaction carrier under formation of complexes. Fluorescent dyes bound to the first components and/or the second components are excited in the surface area of the planar optical waveguide, preferably by the evanescent field of excitation light coupled into the planar optical waveguide, for emitting fluorescent light.