In the scope of this research, the direct liquefaction (DL) of microalgae (Spirulina, Spartina alterniflora) and soy protein was performed in a co-solvent system consisted of water and ethanol (EWCS). We investigated the effect of reaction time, reaction temperature, an alkaline catalyst (Na2CO3), and the Ethanol-Water Co-Solvent system on the liquefaction yields and bio-oil properties. The outcome of the experiments elucidated a bio-oil yield of 49.4 %, 50.2 % and 42.7 % for Spirulina, Spartina alterniflora and Soy protein respectively in which it is much higher than the HTL runs with pure water indicating the positive effect of co-solvent on the liquefaction, and for catalytic runs the bio-oil yields were 53.7%, 50.2%, and 31.6% respectively. When compared to non-catalytic DL, Na2CO3 relatively increased the bio-oil yield of the algae samples and decreased it for the Soy protein samples. The GC-MS and FT-IR analyses displayed that there are some differences in the chemical composition and the content of compounds among the bio-oils, where the significant components were esters, ketones, amides, acids, and nitrogen-containing heterocycles. Apart from its influence on the product yield, the usage of Na2CO3 showed no significant impact on the properties of the bio-oil.