To mitigate the energy crisis and the environmental damage from fossil fuels exploration to combustion, much attention has been focused on liquid biofuel production from algae to reduce CO2 emission and dependence on petroleum. Among the existing algae-to-biofuels technologies, the hydrothermal treatment has been proposed as an attractive one since the produced bio-oil has lower oxygen content than pyrolysis, and the dewatering step of the feedstock is not necessary. However, much biomass residue will be produced associated with the oil extraction from algae, which should be discharged as wastes. Especially the aqueous fraction accounts for the major part of the products. In this study, a green microalgae obtained from TISTR (Thai Institute of Science and Technology Research), named No.8511, was processed under different hydrothermal conditions to investigate the properties of aqueous phase products in terms of the nutrient content. Hydrothermal treatment was conducted at different concentrations of algae (from 5 % to 30 %) and temperature ranges (from 210°C to 290°C). The major nutrition elements and trace metal elements in the aqueous phase were quantified and analyzed. The results showed that a considerable nutrition recovery in aqueous part is possible.