Ancient mummies suffer from degradation as a result of the improper conditions which are changing both the chemical and physical properties of the materials. This study aims to ex-plain the chemical changes of an Egyptian mummy dating back to the late period. Multiple analytical techniques have been executed to characterize the different components of the mummy: optical microscopy, stereo microscopy, scanning electron microscopy-energy dis-persive X-ray spectroscopy, attenuated total reflection-Fourier transform infrared spectrosco-py, Raman spectroscopy, X-ray diffraction, thermogravimetric analysis, differential thermal analysis, and differential scanning calorimetry. The results revealed that the Natron salt exist-ed over the linen wraps and also the hydroxyapatite and collagen as chemical components of the bone with the presence of the mastic resin and beeswax as embalming materials. The in-correct packing method had a negative effect through which the surrounding humidity around the mummy's body accelerated the reaction between the water vapor and the mummy's components. The water molecules of humidity interacted with the Natron salt to form a basic medium, and the humid conditions promoted the microbial and insect activity. The analytical investigation showed the fabric embrittlement in the wrapping and the diagenetic alterations in the bone.