Optical waveguide (OWG) absorption spectroscopy makes use of an evanescent field to detect the polarized absorption spectra of sub-monomolecular adlayers. This technique is suitable for the investigation of adsorption kinetics at the solid/liquid interface of dyes, pigments, fluorescent molecules, quantum dots, metallic nanoparticles, and proteins with chromophores. In this work, a time-resolved optical waveguide spectrometer was constructed using a tungsten-halogen lamp, a prism-coupled thin-filmglass waveguide, and a charge-coupled device (CCD) spectral analyzer. The adsorption properties of rhodamine 6G(R6G) and methylene blue (MB) were investigated using this apparatus. By comparing the transverse electric (TE) and transverse magnetic (TM) polarized absorption spectra, the R6G molecules were found to adsorb onto the glass surface as monomers and dimers while MB adsorbed mostly as high-order aggregates. The average orientation angles of the adsorbed dye molecules were also estimated.