Investigations of the physical and chemical structure of archaeological fibresArchaeological fibres can be defined as natural fibres that belong to different time periods, which found in cemeteries or excavation sites. The preservation conditions cause degradation, mineralisation and sometimes a complete deterioration of these fibres, because the chemical and physical structure of the fibres changed over time in response to the specific burial environments. The ancient fibres from different archaeological sites were analysed by several non destructive analytical techniques such as optical Microscopy, Environmental Scanning Electron Microscopy, Attenuated Total Reflectance FTIR and Wide Angle X-Ray Scattering Analysis as well as destructive analytical techniques such as Scanning Electron Microscopy, Transmission Fourier Transform Infrared Spectroscopy, Energy Dispersive X-Ray Spectroscopy and Differential Scanning Calorimetry. These analytical techniques showed that keratin fibres from a central European climate have a larger damage at the fibre surface compared with frozen conditions. While bog conditions were the best in preserving the surface. FTIR analysis provides information about cystine oxidation changes in keratin fibres. For all ancient keratin fibres showed a silica peak at 1030 cm-1 which affected the symmetric cysteic acid peak at 1040 cm-1. For this reason the asymmetrical cysteic acid peak 1175 cm-1 was used for identification of cystine oxidation changes. Transmission FTIR gives a better view of the overall chemical changes in both cortex and cuticle compared to ATR analysis. All ancient wools and highly medullated Iceman deer hairs showed the highest concentration of cysteic acid compared with human hair and goat hair. Also it was shown that warm conditions have bigger effect on both the degree of oxidation of cystine and the ions uptake from the environment. The modulated DSC analysis gives a better view on the degree of degradation of hair proteins compared to WAXS analysis. To get a reliable result it is important to correct the DSC data according to the protein content of the fibre.