In this article, the evaluation of deterioration stage of five archaeological waterlogged woods excavated at Thang Long Imperial Citadel site in 2022. The results of wood species identification and assessement of the current detertioration status of 848 samples showed the diversity of wood species and the degree of damage. The classification results showed that there are 17 species: Cau (Areca catechu), Mit (Artocarpus sp.), Dau da dat (Baccaurea ramiflora), Che (Camellia sp.), De (Castanopsis tribuloides), Lim (Erythrophleum fordii), Sung (Ficus racemosa), Sen (Madhuca sp.), Xoai (Mangifera indica), Xoan (Melia azedarach L.), Gioi (Michelia sp.), Thong (Pinus sp.), Thong tre (Podocarpus sp.), Bo hon (Sapindus sp.), Gu (Sindora siamensis), Chieu lieu (Terminalia sp.), Tau (Vatica sp.). The destruction assessment results showed that 848 wood samples were divided into 3 groups of deterioration. The Dau da dat (Baccaurea ramiflora), Sung (Ficus racemosa), Xoan (Melia azedarach L.), Bo hon (Sapindus sp.) was under heavily damaged. Meanwhile, the well-known species including Lim (Erythrophleum fordii), Sen (Madhuca sp.), Tau (Vatica sp.), Gu (Sindora siamensis), Che (Camellia sp.) were classified into 3 groups of deterioration, stand at 33% of total samples investigated. The research results provided the basis for future establishing a long-term conservation treatment process for each type and derterioration degree of historical woods.

Keywords: Archaeological waterlogged wood × Basic density × Moisture × Deterioration × Conservation treatment