The use of low cost coated ink jet papers as a replacement for silica coatings has become more common lately. These novel paper grades consist of components typical for conventional printing papers, but have generally been modified to improve ink jet printability. However, knowledge of the fastness properties obtained with such papers is, to date, quite limited. The objective of this study was to clarify the effects of a coating polymer system on the light fastness of ink jet prints on kaolin coated papers. This was studied with FTIR and Raman spectroscopic methods using experimental dye based inks and papers with a known composition. The data on light fastness were consistent with the hypotheses of the study. The light fastness of ink jet prints was affected by both the physical and the chemical properties of the coating. The light fastness of the prints was improved when the porosity of the coating decreased as a result of increased binder content. This behavior could be observed for all coatings independent of the polymer types. The chemical stabilization of the colorants in consequence of hydrogen bonding to coating polymers was found to improve light fastness in PVA coatings.