Abstract: The synthesis of a nano-composite, composed of hydroxyapatite (HA) nanoparticles dispersed in polyethylene glycol (PEG) applicable for long-term preservation of historical leather and parchment samples. The nano-composite is synthesized through a simple method by a two phase mixing process at ambient temperature. The mechanical behavior analysis of goat historical leather treated with the prepared nano-composite revealed more softness, better mechanical properties and less structural changes in comparison with the untreated sample. Furthermore, thermal analysis results have confirmed that nano-composite treatment causes a softer amorphous structure with higher water content, more structural homogeneity, and the temperature that maximum weight losing occurred is higher than those for the untreated sample.